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evolution
BlaC is a class A beta-lactamase
evolution
comparison of the structures of subclass B1 metallo-beta-lactamases IMP-1 and IMP-2, which have an 85% amino acid identity, suggests that the amino acid substitution at position 68 on a beta-strand (beta3) (Pro in IMP-1 versus Ser in IMP-2) may be a staple factor affecting the flexibility of loop 1 (comprising residues at positions 60-66, EVNGWGV). In the IMP-1 structure, loop 1 adopts an open, disordered conformation. Comparison of the active site structure between IMP-1 and IMP-2, loop 1 of IMP-2 forms a closed conformation in which the side chain of Trp64, involved in substrate binding, is oriented so as to cover the active site, even though there is an acetate ion in the active site of both IMP-1 and IMP-2. Loop 1 of IMP-2 has a more flexible structure in comparison to IMP-1 due to having a Ser residue instead of the Pro residue at position 68, indicating that this difference in sequence may be a trigger to induce a more flexible conformation in loop 1
evolution
metallo-beta-lactamases (MBLs) belong to the protein family of beta-lactamases, a group of enzymes that deactivate beta-lactam antibiotics by cleaving the amide bond in the beta-lactam ring, the enzyme belongs to the molecular class B, subclass B1. The Ambler class B beta-lactamase shares 39% and 29% amino acid identity with IMP-1 and VIM-2, from a Pseudomonas aeruginosa hospital isolate, respectively. Active-site residues that are coordinating zinc ions are conserved among all three subclasses
evolution
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PER-2 belongs to a small group of extended-spectrum beta-lactamases. Enzyme PER-2 is defined by the presence of a singular trans bond between residues 166 to 167, which generates an inverted omega loop, an expanded fold of this domain that results in a wide active site cavity that allows for efficient hydrolysis of antibiotics like the oxyimino-cephalosporins, and a series of exclusive interactions between residues not frequently involved in the stabilization of the active site in other class A beta-lactamases. PER beta-lactamases might be included within a cluster of evolutionarily related enzymes harboring the conserved residues Asp136 and Asn179
evolution
the enzyme is a metallo-beta-lactamase of subgroup B1a
evolution
the enzyme is a metallo-beta-lactamase of subgroup B1b
evolution
the enzyme is a metallo-beta-lactamase of subgroup B2
evolution
the enzyme is a metallo-beta-lactamase of subgroup B3
evolution
the POM-1 metallo-beta-lactamase is a subclass B3 resident enzyme
evolution
EstSRT1 is a family VIII carboxylesterase. The enzyme contains a large alpha/beta domain and a small alpha-helical domain and harbors three catalytic residues, Ser71, Lys74, and Tyr160, in the cavity at the domain interface, similarly to other family VIII carboxylesterases. Comparison of the structures of EstSRT1 and EstU1, a family VIII carboxylesterase with no hydrolytic activity toward bulky oxyimino cephalosporins, reveals that EstSRT1 has a smaller active site, despite its extended substrate range. The B-factors of the active site segments that can potentially contact with the oxyimino groups and the R2 side chains of oxyimino cephalosporins are higher in EstSRT1 than in EstU1, thus suggesting the role of the active site's structural flexibility in the extension of EstSRT1's substrate spectrum
evolution
extended-spectrum beta-lactamases (ESBL)-producing Enterobacteriaceae from spring waters can be a thread to human health. ESBL-producing Enterobacteriaceae were found in four out of 50 sampled spring waters (4/50, 8.0%) and a total of 16 non-duplicate ESBL-producing Enterobacteriaceae are obtained, including 13 Escherichia coli and three Klebsiella pneumoniae strains. All 16 nonduplicate ESBL-producing Enterobacteriaceae isolates harbour genes encoding CTX-M ESBLs, among which six expressed CTX-M-15, five produced CTX-M-14, three produced CTX-M-55 and two expressed CTX-M-27. Four multilocus sequence types (ST) are found and ST131 is the dominant type (8/16, 50.0%). The contamination of ESBL-producing Enterobacteriaceae are present in spring waters of Mountain Tai
evolution
extended-spectrum beta-lactamases (ESBL)-producing Enterobacteriaceae from spring waters can be a thread to human health. ESBL-producing Enterobacteriaceae were found in four out of 50 sampled spring waters (4/50, 8.0%) and a total of 16 non-duplicate ESBL-producing Enterobacteriaceae are obtained, including 13 Escherichia coli and three Klebsiella pneumoniae strains. All 16 nonduplicate ESBL-producing Enterobacteriaceae isolates harbour genes encoding CTX-M ESBLs, among which six expressed CTX-M-15, five produced CTX-M-14, three produced CTX-M-55 and two expressed CTX-M-27. Four multilocus sequence types (ST) are found and ST131 is the dominant type (8/16, 50.0%). The contamination of ESBL-producing Enterobacteriaceae are present in spring waters of Mountain Tai
evolution
functionally classifying and characterising serine beta-lactamases: proposal of a grouping of serine beta-lactamases that more consistently captures and rationalizes the existing three classification schemes: classes (A, C and D, which vary in their implementation of the mechanism of action), types (that largely reflect evolutionary distance measured by sequence similarity), and variant groups (which largely correspond with the Bush-Jacoby clinical groups). Analysis of Class A enzymes, overview
evolution
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genotyping and phenotyping of Escherichia coli strains with beta-lactamase activity in faeces from ducks, phylogenetic analysis. 5 (38.46%) Salmonella isolates are found to harbour gene blaCTX-M. Six Samonella isolates (46.15%) are detected as AmpC producers possessing gene blaAmpC. Significantly higher occurrence of beta-lactamase and biofilm producing Enterobacteriaceae isolates is detected in backyard ducks than organized farms
evolution
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genotyping and phenotyping of Escherichia coli strains with beta-lactamase activity in faeces from ducks, phylogenetic analysis. Among the 87 phenotypically beta-lactamase producing Escherichia coli, 19 (17.43%), 6 (5.05%) and 15 (13.76%) isolates possess genes blaTEM, blaSHV, and blaCTX-M genes, respectively. Beta-lactamase producing Escherichia coli isolates belong to 14 different serogroups such as O1, O2, O3, O5, O7, O8, O35, O83, O84, O88, O119, O128, O145 and O157. 87 Escherichia coli isolates (79.82%) are detected as AmpC producers possessing gene blaAmpC. Significantly higher occurrence of beta-lactamase and biofilm producing Enterobacteriaceae isolates is detected in backyard ducks than organized farms
evolution
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genotyping and phenotyping of Escherichia coli strains with beta-lactamase activity in faeces from ducks, phylogenetic analysis. In Klebsiella pneumoniae 10, 3, and 4 isolates possess blaTEM, blaSHV, and blaCTX-M genes, respectively. The sequences of selected PCR products are found 98% cognate with blaCTX-M-9, blaSHV-12 and blaTEM-1. 13 Klebsiella pneumoniae isolates (43.33%) are detected as AmpC producers possessing gene blaAmpC. Significantly higher occurrence of beta-lactamase and biofilm producing Enterobacteriaceae isolates is detected in backyard ducks than organized farms
evolution
genotyping of bla genes in pAmpC-producing Escherichia coli strains, and antimicrobial resistance profiles, overview. Bacteria overexpressing AmpC beta-lactamases are usually resistant to all beta-lactam antibiotics, except cefepime, cefpirome, and carbapenems, which is an important clinical concerns because the bacteria often express a multidrug-resistant phenotype, leaving limited therapeutic options
evolution
phenotype and genotype of the AmpC-positive strains. Beta-lactamases and other resistance mechanisms are characterized in Enterobacteriaceae isolates recovered from healthy human faecal samples, focusing on the ampC beta-lactamase genes. 50 human faecal samples are obtained, and 70 Enterobacteriaceae bacteria are isolated: 44 Escherichia coli, 4 Citrobacter braakii, 9 Citrobacter freundii, 8 Enterobacter cloacae, 1 Proteus mirabilis, 1 Proteus vulgaris, 1 Klebsiella oxytoca, 1 Serratia sp. and 1 Cronobacter sp. A high percentage of resistance to ampicillin is detected (57 %), observing the AmpC phenotype in 22 isolates (31 %) and the extended spectrum beta-lactamase (ESBL) phenotype in 3 isolates. AmpC molecular characterization shows high diversity into blaCMY and blaACT genes from Citrobacter and Enterobacter species, respectively, with low clonality among them. Clonal relationships among Citrobacter spp. and among Enterobacter spp. isolates, molecular typing and phylogenetic analysis, overview
evolution
phenotype and genotype of the AmpC-positive strains. Beta-lactamases and other resistance mechanisms are characterized in Enterobacteriaceae isolates recovered from healthy human faecal samples, focusing on the ampC beta-lactamase genes. 50 human faecal samples are obtained, and 70 Enterobacteriaceae bacteria are isolated: 44 Escherichia coli, 4 Citrobacter braakii, 9 Citrobacter freundii, 8 Enterobacter cloacae, 1 Proteus mirabilis, 1 Proteus vulgaris, 1 Klebsiella oxytoca, 1 Serratia sp. and 1 Cronobacter sp. A high percentage of resistance to ampicillin is detected (57 %), observing the AmpC phenotype in 22 isolates (31 %) and the extended spectrum beta-lactamase (ESBL) phenotype in 3 isolates. AmpC molecular characterization shows high diversity into blaCMY and blaACT genes from Citrobacter and Enterobacter species, respectively, with low clonality among them. Clonal relationships among Citrobacter spp. and among Enterobacter spp. isolates, molecular typing and phylogenetic analysis, overview
evolution
phenotype and genotype of the AmpC-positive strains. Beta-lactamases and other resistance mechanisms are characterized in Enterobacteriaceae isolates recovered from healthy human faecal samples, focusing on the ampC beta-lactamase genes. 50 human faecal samples are obtained, and 70 Enterobacteriaceae bacteria are isolated: 44 Escherichia coli, 4 Citrobacter braakii, 9 Citrobacter freundii, 8 Enterobacter cloacae, 1 Proteus mirabilis, 1 Proteus vulgaris, 1 Klebsiella oxytoca, 1 Serratia sp. and 1 Cronobacter sp. A high percentage of resistance to ampicillin is detected (57 %), observing the AmpC phenotype in 22 isolates (31 %) and the extended spectrum beta-lactamase (ESBL) phenotype in 3 isolates. AmpC molecular characterization shows high diversity into blaCMY and blaACT genes from Citrobacter and Enterobacter species, respectively, with low clonality among them. Clonal relationships among Citrobacter spp. and among Enterobacter spp. isolates, molecular typing and phylogenetic analysis, overview
evolution
the purified soluble form of recombinant MSMEG_4455 shows a beta-lactam hydrolysis pattern similar to group 2a penicillinase. The BlaA enzyme of H37Ra is identical to BlaC of H37Rv
evolution
The PWP triad is sequentially and structurally conserved in class a beta-lactamase family, the evolutionarily conserved allosteric site modulates beta-lactamase activity
evolution
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the purified soluble form of recombinant MSMEG_4455 shows a beta-lactam hydrolysis pattern similar to group 2a penicillinase. The BlaA enzyme of H37Ra is identical to BlaC of H37Rv
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evolution
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BlaC is a class A beta-lactamase
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evolution
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the purified soluble form of recombinant MSMEG_4455 shows a beta-lactam hydrolysis pattern similar to group 2a penicillinase. The BlaA enzyme of H37Ra is identical to BlaC of H37Rv
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malfunction
deletion of gene blaMab dramatically reduces the MIC values of penicillins and first-, second- and third generation cephalosporins (except ceftazidime)
malfunction
inactivation of the cell surface-expressed serine hydrolase and class A beta-lactamase BlaC in Mycobacterium tuberculosis (Mtb) causes increased susceptibility to beta-lactam antibiotics
malfunction
mutation at the glutamate residues in the omega-loop of SHV-14, i.e. E126, E164, and E167, can considerably modulate the beta-lactam sensitivity and reduce hydrolysis. The mutations in SHV-14 render beta-lactamase inhibitors more efficient. The mutations alter the active site configuration of SHV-14
malfunction
while point mutations in the PWP triad preserve the overall secondary structures around the allosteric site, they result in a more open and dynamic global structure with decreased chemical stability and increased aggregation propensity. These mutant enzymes with a less compact hydrophobic core around the allosteric site display significant activity loss
malfunction
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deletion of gene blaMab dramatically reduces the MIC values of penicillins and first-, second- and third generation cephalosporins (except ceftazidime)
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malfunction
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inactivation of the cell surface-expressed serine hydrolase and class A beta-lactamase BlaC in Mycobacterium tuberculosis (Mtb) causes increased susceptibility to beta-lactam antibiotics
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malfunction
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inactivation of the cell surface-expressed serine hydrolase and class A beta-lactamase BlaC in Mycobacterium tuberculosis (Mtb) causes increased susceptibility to beta-lactam antibiotics
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malfunction
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mutation at the glutamate residues in the omega-loop of SHV-14, i.e. E126, E164, and E167, can considerably modulate the beta-lactam sensitivity and reduce hydrolysis. The mutations in SHV-14 render beta-lactamase inhibitors more efficient. The mutations alter the active site configuration of SHV-14
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physiological function
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plays a significant role in limiting susceptibility to penicillins and cephalosporins. The contribution of BlaB, a class C enzyme, is less profound and is limited primarily to cephalosporin susceptibility
physiological function
GES beta-lactamases are important contributors to carbapenem resistance in clinical bacterial pathogens
physiological function
New Delhi MBL (NDM)-1 is a clinically significant metallo beta-lactamase
physiological function
role of beta-lactamase BlaMab in beta-lactam resistance, overview
physiological function
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subclass B3 metallo-beta-lactamase SMB-1 that confers carbapenem resistance
physiological function
the constitutively expressed, chromosomally-encoded beta-lactamase (BlaC) is the enzyme responsible for the intrinsic resistance to beta-lactam antibiotics in Mycobacterium tuberculosis
physiological function
the enzyme is involved in antibiotic resistance, catalyzing the hydrolysis of antibiotics such as benzylpenicillin and imipenem
physiological function
84 multidrug-resistant Klebsiella pneumoniae (MDR-KP) clinical isolates studied, 19 isolates exhibit high level resistance to amikacin mediated by the production of the 16S rRNA methylase. CTX-M genes were found in all of the isolates. Among these armA- or rmtB/CTX-M-producing Klebsiella pneumoniae isolates, 31.6% carry the carbapenemase genes (blaKPC-2 [26.3%], blaIMP-4 [10.5%], and blaNDM-1 [5.3%]), which made them resistant to imipenem
physiological function
chromosomal AmpC beta-lactamases are cephalosporinases, often inducible in the presence of certain beta-lactams such as cefoxitin or imipenem, but that confer a broad beta-lactam resistance profile when they are derepressed or hyperproduced or plasmid mediated. These AmpC enzymes, including plasmidmediated and derepressed or hyperproduced chromosomal AmpCs, suppose a huge repercussion in clinical treatments because they are active against all beta-lactams (including cephamycins), except fourth-generation cephalosporins and carbapenems
physiological function
chromosomal AmpC beta-lactamases are cephalosporinases, often inducible in the presence of certain beta-lactams such as cefoxitin or imipenem, but that confer a broad beta-lactam resistance profile when they are derepressed or hyperproduced or plasmid mediated. These AmpC enzymes, including plasmidmediated and derepressed or hyperproduced chromosomal AmpCs, suppose a huge repercussion in clinical treatments because they are active against all beta-lactams (including cephamycins), except fourth-generation cephalosporins and carbapenems
physiological function
chromosomal AmpC beta-lactamases are cephalosporinases, often inducible in the presence of certain beta-lactams such as cefoxitin or imipenem, but that confer a broad beta-lactam resistance profile when they are derepressed or hyperproduced or plasmid mediated. These AmpC enzymes, including plasmidmediated and derepressed or hyperproduced chromosomal AmpCs, suppose a huge repercussion in clinical treatments because they are active against all beta-lactams (including cephamycins), except fourth-generation cephalosporins and carbapenems
physiological function
extensive production of SHV-14 beta-lactamase makes Klebsiella pneumoniae resistant to beta-lactams. The presence of an omega-loop has been reported to influence the beta-lactamase activity, which is also present in SHV-14
physiological function
AB702957
MacQ is a bifunctional enzyme that confers both quorum quenching and antibiotic resistance on strain MRS7. The enzyme is capable of degrading not only various N-acylhomoserine lactones (AHLs) derivatives but also multiple beta-lactam antibiotics by deacylation activities. Recombinant MacQ confers multiple beta-lactam antibiotic resistance on an Escherichia coli host strain by hydrolyzing beta-lactam antibiotics. The N-acylhomoserine lactone acylase (AHL acylase) activity is responsible for disrupting cell-cell communication (quorum sensing) in bacteria
physiological function
metallo-beta-lactamase (MBL) is a class of enzyme that catalyzes the hydrolysis of a broad range of beta-lactam antibiotics leading to the development of drug resistance in bacteria
physiological function
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role of beta-lactamase BlaMab in beta-lactam resistance, overview
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physiological function
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the constitutively expressed, chromosomally-encoded beta-lactamase (BlaC) is the enzyme responsible for the intrinsic resistance to beta-lactam antibiotics in Mycobacterium tuberculosis
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physiological function
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extensive production of SHV-14 beta-lactamase makes Klebsiella pneumoniae resistant to beta-lactams. The presence of an omega-loop has been reported to influence the beta-lactamase activity, which is also present in SHV-14
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additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution. Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution.Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution.Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution.Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution.Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution.Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution.Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
different genotypes of the New Delhi metallo beta-lactamase are identified: the substitutions do not affect the overall folds of the enzyme variants, within limits of detection. Differences in thermal stabilities are observed. kcat/KM values are similar for carbapenem and penicillin substrates for NDM variants, but differences in kinetics are observed for cephalosporin substrates. Apparent substrate inhibition is observed with nitrocefin for variants containing the M154L substitution. In all cases, cefoxitin and ceftazidime are poorly hydrolysed. Clinically observed substitutions can make substantial differences in thermodynamic stability, suggesting that this may be a factor in metallo beta-lactamase evolution.Comparative analysis of the beta-lactam susceptibility of the NDM variants in Escherichia coli, overview
additional information
in GES-2 an extensive hydrogen-bonding network between the acyl-enzyme complex and the active site water attenuates activation of this water molecule, which results in poor deacylation by this enzyme
additional information
in GES-2 an extensive hydrogen-bonding network between the acyl-enzyme complex and the active site water attenuates activation of this water molecule, which results in poor deacylation by this enzyme
additional information
in GES-2 an extensive hydrogen-bonding network between the acyl-enzyme complex and the active site water attenuates activation of this water molecule, which results in poor deacylation by this enzyme
additional information
Mox-1 is a unique plasmid-mediated class C beta-lactamase. Structure comparison with other beta-lactamases shows that two region in Mox 1, amino acid residues 214 to 216 positioned in the omega loop and the other in the N-terminus of the B3 beta-strand corresponding to amino acid residues 303 to 306, having significant structural flexibility of these regions, may impact the recognition and binding of substrates in Mox-1 leading to the unique substrate profile of the enzyme, overview. A substrate-induced conformational change underlies the basis of the hydrolytic profile of Mox-1 beta-lactamase, active site structure of enzyme Mox-1, overview
additional information
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secondary structures and conserved motifs of PER-2 and other class A beta-lactamases, presence of a hydrogen-bond network connecting Ser70-Gln69-water-Thr237-Arg220 that might be important for the proper activity and inhibition of the enzyme, strcture comparisson, simulation and modeling, overview
additional information
the catalytic mechanism of BlaC relies on three highly conserved active site residues, Lys73 and Glu166, which are involved in the activation of the acylating nucleophile Ser70 and the activation of the active site water molecule for deacylation, respectively. Lys73 is essential for the acylation step
additional information
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the catalytic mechanism of BlaC relies on three highly conserved active site residues, Lys73 and Glu166, which are involved in the activation of the acylating nucleophile Ser70 and the activation of the active site water molecule for deacylation, respectively. Lys73 is essential for the acylation step
additional information
the marine enzyme is highly salt tolerant and cold active
additional information
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structural basis of the hydrolytic activity of EstSRT1 toward bulky oxyimino antibiotics. Structural comparison between EstSRT1 and the EstU1/cephalothin complex
additional information
structural basis of the hydrolytic activity of EstSRT1 toward bulky oxyimino antibiotics. Structural comparison between EstSRT1 and the EstU1/cephalothin complex
additional information
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structural basis of the hydrolytic activity of EstSRT1 toward bulky oxyimino antibiotics. The three catalytic residues are Ser71, Lys74, and Tyr160. Structural comparison between EstSRT1 and the EstU1/cephalothin complex
additional information
structural basis of the hydrolytic activity of EstSRT1 toward bulky oxyimino antibiotics. The three catalytic residues are Ser71, Lys74, and Tyr160. Structural comparison between EstSRT1 and the EstU1/cephalothin complex
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characterization of pAmpC-producing Escherichia coli strains isolated from chicken carcasses and human infection in a restrict area and to determine their antimicrobial resistance profiles, and molecular type by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis. The blaCMY-2 gene is identified in all pAmpC-producing Escherichia coli strains
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characterization of pAmpC-producing Escherichia coli strains isolated from chicken carcasses and human infection in a restrict area and to determine their antimicrobial resistance profiles, and molecular type by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis. The blaCMY-2 gene is identified in all pAmpC-producing Escherichia coli strains
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close to 80% of blaTEM-1 and blaSHV-12 are linked to IS26 while 90% or more of blaCTX-Ms and blaCMYs are linked to ISEcp1. ISAba125 is located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants are available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 are cotransferred. The dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of antibiotics resistance determinants in collection of clinical Klebsiella pneumoniae in China, overview
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close to 80% of blaTEM-1 and blaSHV-12 are linked to IS26 while 90% or more of blaCTX-Ms and blaCMYs are linked to ISEcp1. ISAba125 is located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants are available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 are cotransferred. The dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of antibiotics resistance determinants in collection of clinical Klebsiella pneumoniae in China, overview
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close to 80% of blaTEM-1 and blaSHV-12 are linked to IS26 while 90% or more of blaCTX-Ms and blaCMYs are linked to ISEcp1. ISAba125 is located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants are available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 are cotransferred. The dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of antibiotics resistance determinants in collection of clinical Klebsiella pneumoniae in China, overview
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close to 80% of blaTEM-1 and blaSHV-12 are linked to IS26 while 90% or more of blaCTX-Ms and blaCMYs are linked to ISEcp1. ISAba125 is located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants are available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 are cotransferred. The dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of antibiotics resistance determinants in collection of clinical Klebsiella pneumoniae in China, overview
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close to 80% of blaTEM-1 and blaSHV-12 are linked to IS26 while 90% or more of blaCTX-Ms and blaCMYs are linked to ISEcp1. ISAba125 is located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants are available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 are cotransferred. The dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of antibiotics resistance determinants in collection of clinical Klebsiella pneumoniae in China, overview
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close to 80% of blaTEM-1 and blaSHV-12 are linked to IS26 while 90% or more of blaCTX-Ms and blaCMYs are linked to ISEcp1. ISAba125 is located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants are available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 are cotransferred. The dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of antibiotics resistance determinants in collection of clinical Klebsiella pneumoniae in China, overview
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consumption of antibiotic through feed or during therapy is considered as potential reason for generation of antimicrobial resistant bacteria in birds
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consumption of antibiotic through feed or during therapy is considered as potential reason for generation of antimicrobial resistant bacteria in birds
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consumption of antibiotic through feed or during therapy is considered as potential reason for generation of antimicrobial resistant bacteria in birds
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enzyme structure-function relationship in silico analysis, overview. Residues E193 and Y194 of the omega-like loop might have importance in strengthening hydrogen bond network around the active site, though involvement of tyrosine is rare for beta-lactamase activity. Y194 is the key for beta-lactamase activity of MSMEG_4455
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enzyme structure-function relationship in silico analysis, overview. Residues E193 and Y194 of the omega-like loop might have importance in strengthening hydrogen bond network around the active site, though involvement of tyrosine is rare for beta-lactamase activity. Y194 is the key for beta-lactamase activity of MSMEG_4455
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Escherichia coli remains as one of the most important bacteria causing infections in pediatrics and producing extended-spectrum beta-lactamases (ESBLs) making them resistant to beta-lactam antibiotics. Multidrug resistant extended-spectrum beta-lactamase-producing Escherichia coli strains among uropathogens of pediatrics in north of Iran are isolated and tested by PCR for the presence or absence of CTX, TEM, SHV, GES, and VEB beta-lactamase genes. Genotyping reveals that the TEM gene is the most prevalent (49%) followed by SHV (44%), CTX (28%), VEB (8%), and GES (0%) genes. The ESBL-producing Escherichia coli isolates are susceptible to carbapenems (66%) and amikacin (58%) and show high resistance to cefixime (99%), colistin (82%), and ciprofloxacin (76%). Carbapenems are the most effective antibiotics against ESBl-producing Escherichia coli in urinary tract infection in north of Iran
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Glu152 and Ser191 are the key residues required for the metallo-beta-lactamase activity of strain NDM-7. Three-dimensional structure homology modelling of wild-type BlaNDM-7 and mutant enzymes
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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mechanism of antibiotics resistance, overview
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structure-based classification of beta-lactamases, functional determinants between the Class A, C, D beta-lactamases and of sites in the active sites of class A serine beta-lactamases likely to be affecting phenotype
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structure-based classification of beta-lactamases, functional determinants between the Class A, C, D beta-lactamases and of sites in the active sites of class A serine beta-lactamases likely to be affecting phenotype
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structure-based classification of beta-lactamases, identification functional determinants between the Class A, C, D beta-lactamases and of sites in the active sites of class A serine beta-lactamases likely to be affecting phenotype. Isozyme TEM-1 is a class A type 1 enzyme
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structure-based classification of beta-lactamases, identification functional determinants between the Class A, C, D beta-lactamases and of sites in the active sites of class A serine beta-lactamases likely to be affecting phenotype. Isozyme TEM-1 is a class A type 1 enzyme
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structure-function analysis, molecular dynamics simulation and modeling, overview
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substrate binding to active site residues of SHV-14 wild-type and mutant enzyme proteins, structures, overview
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substrate binding to active site residues of SHV-14 wild-type and mutant enzyme proteins, structures, overview
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the evolutionarily conserved PWP triad located at the N-terminus of the H10 helix directly interacts with the allosteric site in TEM-1 beta-lactamase and regulates its activity. The PWP triad is an evolutionarily conserved motif unique to class A beta-lactamases aligning its allosteric site. The H10 helix C-terminus forms part of the active site, specifically K243 participating in catalysis and substrate binding, while P226-W229-P252 (PWP triad) residues at the N-terminus participate in aromatic ring stacking that stabilize the helix. Together with the T-shaped aromatic interaction between W229 and W290, this extensive interaction network modulates the flexibility of H10 and its interactions with other secondary structural elements in the hydrophobic inhibitor binding pocket, suggesting the contribution of these residues to allostery. Structure comparisons, overview
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Glu152 and Ser191 are the key residues required for the metallo-beta-lactamase activity of strain NDM-7. Three-dimensional structure homology modelling of wild-type BlaNDM-7 and mutant enzymes
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enzyme structure-function relationship in silico analysis, overview. Residues E193 and Y194 of the omega-like loop might have importance in strengthening hydrogen bond network around the active site, though involvement of tyrosine is rare for beta-lactamase activity. Y194 is the key for beta-lactamase activity of MSMEG_4455
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the catalytic mechanism of BlaC relies on three highly conserved active site residues, Lys73 and Glu166, which are involved in the activation of the acylating nucleophile Ser70 and the activation of the active site water molecule for deacylation, respectively. Lys73 is essential for the acylation step
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enzyme structure-function relationship in silico analysis, overview. Residues E193 and Y194 of the omega-like loop might have importance in strengthening hydrogen bond network around the active site, though involvement of tyrosine is rare for beta-lactamase activity. Y194 is the key for beta-lactamase activity of MSMEG_4455
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substrate binding to active site residues of SHV-14 wild-type and mutant enzyme proteins, structures, overview
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Mox-1 is a unique plasmid-mediated class C beta-lactamase. Structure comparison with other beta-lactamases shows that two region in Mox 1, amino acid residues 214 to 216 positioned in the omega loop and the other in the N-terminus of the B3 beta-strand corresponding to amino acid residues 303 to 306, having significant structural flexibility of these regions, may impact the recognition and binding of substrates in Mox-1 leading to the unique substrate profile of the enzyme, overview. A substrate-induced conformational change underlies the basis of the hydrolytic profile of Mox-1 beta-lactamase, active site structure of enzyme Mox-1, overview
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