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DELTA1-227
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mutant enzyme shows no CMP-N-acetylneuraminic acid synthetase activity, mutant enzyme is able to hydrolyze platelet activating factor
DELTA1-229
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mutant enzyme shows no CMP-N-acetylneuraminic acid synthetase activity, mutant enzyme is not able to hydrolyze platelet activating factor
DELTA230-418
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mutant enzyme shows 43% of the wild-type activity with CTP and N-acylneuraminate as substrates, decrease in stability compared to wild-type enzyme
DELTA247-418
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mutant enzyme shows 15% of the wild-type activity with CTP and N-acylneuraminate as substrates, decrease in stability compared to wild-type enzyme
DELTA340-418
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mutant enzyme shows 65% of the wild-type activity with CTP and N-acylneuraminate as substrates, as stable as wild-type enzyme
DELTA384-418
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mutant enzyme shows 31% of the wild-type activity with CTP and N-acylneuraminate as substrates, as stable as wild-type enzyme
DELTA396-418
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mutant enzyme shows 38% of the wild-type activity with CTP and N-acylneuraminate as substrates, as stable as wild-type enzyme
DELTA1-227
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mutant enzyme shows no CMP-N-acetylneuraminic acid synthetase activity, mutant enzyme is able to hydrolyze platelet activating factor
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DELTA340-418
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mutant enzyme shows 65% of the wild-type activity with CTP and N-acylneuraminate as substrates, as stable as wild-type enzyme
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DELTA384-418
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mutant enzyme shows 31% of the wild-type activity with CTP and N-acylneuraminate as substrates, as stable as wild-type enzyme
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DELTA396-418
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mutant enzyme shows 38% of the wild-type activity with CTP and N-acylneuraminate as substrates, as stable as wild-type enzyme
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DELTA408-424
deletion mutant devoid of the second putative nuclear export signal, by immunofluorescent microscopy it is shown that this deletion mutant has an increased nuclear localisation combined with a decreased cytoplasmic localisation
DELTA61-69
deletion mutant devoid of the first putative nuclear export signal, by immunofluorescent microscopy it is shown that is deletion mutant has an increased nuclear localisation combined with a decreased cytoplasmic localisation
K198A
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mutant enzyme is active at moderately reduced level
R199A
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inactive mutant protein
R199A/R202A
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inactive mutant protein
R201A
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mutant enzyme is active at moderately reduced level
R202A
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mutant enzyme shows drastically reduced activity
E162A
the mutant enzyme shows 14.5% activity compared to the wild type enzyme
E162Q
the mutant enzyme shows 15.3% activity compared to the wild type enzyme
F192A
8fold increase on Km value for CTP
F193A
3fold increase on Km value for CTP
N175A
16fold increases in the Km value for CTP and 23fold for N-acetylneuraminate
Q104A
40fold inccrease in Km value for N-acetylneuraminate
Q104E
dramatic loss of activity. Residue involved in metal binding
Q104L
dramatic loss of activity. Residue involved in metal binding
Q104N
dramatic loss of activity. Residue involved in metal binding
Q163A
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mutant displays improved substrate promiscuity
R165A
the mutant enzyme shows 0.163% activity compared to the wild type enzyme
R173A
38fold increase in Km value for N-acetylneuraminate
S31R
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mutant displays improved substrate promiscuity, catalytic activities for substrates N-glycolylneuraminate, N-methylglycolylneuraminate and 8-O-methyl N-acetyl-neuraminate are improved compared to wild-type
Y179A
200fold decrease in kcat value
N35Q
site-directed mutagenesis of the glycosylation site, the mutant shows enzyme activity
N35Q
the mutant shows about 2.3fold increased activity compared to the wild type enzyme
N66Q
site-directed mutagenesis of the glycosylation site, the mutant shows enzyme activity
N66Q
the mutant shows about 1.2fold increased activity compared to the wild type enzyme
D209A
almost complete loss of activity. Residue involved in metal binding
D209A
the mutation is detrimental to enzyme function
D211A
dramatic loss of activity. Residue involved in metal binding
D211A
the mutation is detrimental to enzyme function
K142A
10000fold reduction in kcat with an insignificant, fourfold, rise in Km for CTP
K142A
dramatic loss of activity. Residue involved in metal binding
additional information
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construction of a DELTAN-AaCSS mutant which gives a single band at 517 kDa, but not a smear in the high-molecular mass region. Furthermore, DELTANAaCSS shows in vitro activity to Neu5Ac. Cleavage of the N-terminal hydrophobic region of the CSSs is critical for the enzyme activity
additional information
construction of a DELTAN-AaCSS mutant which gives a single band at 517 kDa, but not a smear in the high-molecular mass region. Furthermore, DELTANAaCSS shows in vitro activity to Neu5Ac. Cleavage of the N-terminal hydrophobic region of the CSSs is critical for the enzyme activity
additional information
presence of four basic clusters BC1-BC4 in the protein sequence. Deletion of BC3 does not impair nuclear import of isoform Cmas1, deletion of BC1 or BC2, individually or in combination, entail retention in the cytoplasm. neither the deletion of BC1 nor BC2 alters enzymatic activity
additional information
presence of four basic clusters BC1-BC4 in the protein sequence. Deletion of BC3 does not impair nuclear import of isoform Cmas1, deletion of BC1 or BC2, individually or in combination, entail retention in the cytoplasm. neither the deletion of BC1 nor BC2 alters enzymatic activity
additional information
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presence of four basic clusters BC1-BC4 in the protein sequence. Deletion of BC3 does not impair nuclear import of isoform Cmas1, deletion of BC1 or BC2, individually or in combination, entail retention in the cytoplasm. neither the deletion of BC1 nor BC2 alters enzymatic activity
additional information
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in contrast to its mammalian counterparts DmCSAS protein begins with an N-terminal sequence rich in hydrophobic amino acids characteristic of a signal/anchoring sequence
additional information
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multiple alignment among the Drosophila melanogaster, human, mouse, Escherichia coli and Neisseria meningitidis CSAS enzymes shows that all proteins are homologous over the length of the catalytic domain
additional information
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replacement of the N-terminal leader sequence of DmCSAS with the human CSAS N-terminal sequence results in the redirection of the chimeric CSAS protein to the nucleus but with concomitant loss of activity
additional information
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a series of deletions from the 3'-end of the CMP-NeuAc synthetase coding region is constructed and expressed in Escherichia coli. As a result, the catalytic domain required for CMP-NeuAc synthetase is found to be in the N-terminal half consisting of amino acids 1229. The C-terminal half consisting of amino acids 228418 exhibits platelet-activating factor acetylhydrolase activity
additional information
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a series of deletions from the 3'-end of the CMP-NeuAc synthetase coding region is constructed and expressed in Escherichia coli. As a result, the catalytic domain required for CMP-NeuAc synthetase is found to be in the N-terminal half consisting of amino acids 1229. The C-terminal half consisting of amino acids 228418 exhibits platelet-activating factor acetylhydrolase activity
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additional information
by deletion mutant analysis it is demonstrated that mouse CSS contains two nuclear export signals which regulate the transport of the protein from nucleus towards cytosol
additional information
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by deletion mutant analysis it is demonstrated that mouse CSS contains two nuclear export signals which regulate the transport of the protein from nucleus towards cytosol
additional information
the two nuclear export signals of mouse CSS are conserved among mammals and fish CSSs but they are not present in bacteria or insect CSS
additional information
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the two nuclear export signals of mouse CSS are conserved among mammals and fish CSSs but they are not present in bacteria or insect CSS
additional information
generation of mouse embryonic stem cell (mESC) lines that lack CMP-Sia synthetase (CMAS) and thereby the ability to activate Sia to CMP-Sia, phenotype, overview. The Cmas targeting strategy uses a targeting vector with diphtheria toxin cassette (DT) to increase homologous recombination. Cmas-/- mESC accumulate intracellular Neu5Ac. alpha2,3- and alpha2,6-Sialylated N-glycans are absent in Cmas-/- mESCs
additional information
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generation of mouse embryonic stem cell (mESC) lines that lack CMP-Sia synthetase (CMAS) and thereby the ability to activate Sia to CMP-Sia, phenotype, overview. The Cmas targeting strategy uses a targeting vector with diphtheria toxin cassette (DT) to increase homologous recombination. Cmas-/- mESC accumulate intracellular Neu5Ac. alpha2,3- and alpha2,6-Sialylated N-glycans are absent in Cmas-/- mESCs
additional information
amino acid sequence alignment of SaV CSS indicate that the C-terminus belongs to the newly discovered SGNH-hydrolase subfamily of serine esterases/lipases
additional information
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amino acid sequence alignment of SaV CSS indicate that the C-terminus belongs to the newly discovered SGNH-hydrolase subfamily of serine esterases/lipases