Activating Compound | Comment | Organism | Structure |
---|---|---|---|
H-protein | upon addition of exogenous unlipoylated H-protein, kcat increases 190fold, in the absence of the lipoic acid moiety on H-protein, the methylamine adduct with pyridoxal 5'-phosphate (aminomethyl-quinonoid intermediate) is released as the product of the GLDC-catalyzed decarboxylation of glycine | Homo sapiens | |
lipoylated H-protein | the presence of the lipoyl moiety on H-protein does not affect the rates of GLDC (or GLDCcoexp)-catalyzed glycine decarboxylation | Homo sapiens | |
additional information | the presence of the lipoyl moiety on H-protein does not affect the rates of GLDC (or GLDCcoexp)-catalyzed glycine decarboxylation further corroborates the suggestion that H-protein (or lipoylated H-protein) does not directly participate in and is not required for release of CO2 from glycine in the formation of the pyridoxal 5'-phosphate-quinonoid intermediate, an important distinction that is contrary to earlier findings | Homo sapiens |
Cloned (Comment) | Organism |
---|---|
recombinant expression of codon optimized C-terminally His6-tagged enzyme GLDC in Escherichia coli strain BL21(DE3), GLDC is expressed either separately (without H-protein) or simultaneously with H-protein, coexpression of His6-tagged enzyme with codon-optimized human H-protein in Escherichia coli strain BL21(DE3) from pJexpress-416 vector | Homo sapiens |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.0003 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme | Homo sapiens | |
0.00031 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme in presence of lipoylated H-protein | Homo sapiens | |
0.00037 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme in presence of H-protein | Homo sapiens | |
1.3 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme in presence of lipoylated H-protein | Homo sapiens | |
2.1 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme in presence of H-protein | Homo sapiens |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | required | Homo sapiens |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
glycine + [glycine-cleavage complex H protein]-N6-lipoyl-L-lysine | Homo sapiens | - |
[glycine-cleavage complex H protein]-S-aminomethyl-N6-dihydrolipoyl-L-lysine + CO2 | - |
r |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P23378 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant His6-tagged enzymes from Escherichia coli strain BL21(DE3) by nickel affinity chromatography and dialysis | Homo sapiens |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
glycine + [glycine-cleavage complex H protein]-N6-lipoyl-L-lysine = [glycine-cleavage complex H protein]-S-aminomethyl-N6-dihydrolipoyl-L-lysine + CO2 | mechanism of the GLDC-catalyzed reaction, detailed overview. GLDC is an unusual PLP-containing alpha-amino acid decarboxylase that removes carbon dioxide from the glycine substrate without releasing the expected amine (methylamine, a metabolic precursor of toxic formaldehyde) as a product. In an unusual decarboxylation mechanism, the resulting aminomethyl moiety is instead transferred to an accessory H-protein. (1) H-Protein is not required for glycine decarboxylation but, instead, is required for the release of the aminomethyl moiety from the quinonoid adduct. (2) Glycine decarboxylation is reversible and presumably proceeds through a stable quinonoid intermediate. (3) The physiological product of glycine decarboxylation is H-protein-S-aminomethyl dihydrolipoyllysine and not methylamine (in the absence of H-protein, the aminomethyl moiety remains as a quinonoid adduct) | Homo sapiens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
glycine + [glycine-cleavage complex H protein]-N6-lipoyl-L-lysine | - |
Homo sapiens | [glycine-cleavage complex H protein]-S-aminomethyl-N6-dihydrolipoyl-L-lysine + CO2 | - |
r | |
glycine + [glycine-cleavage complex H protein]-N6-lipoyl-L-lysine | reversible reaction | Homo sapiens | [glycine-cleavage complex H protein]-S-aminomethyl-N6-dihydrolipoyl-L-lysine + CO2 | - |
r | |
additional information | presence of excess pyridoxal 5'-phosphate is used in the assay mixture to facilitate the displacement of the quinonoid intermediate in the absence of an acceptor for the methylamine moiety (of decarboxylated glycine) to allow multiple enzyme turnovers. Mass spectrometry and 13C NMR spectroscopy are used to determine the products of glycine decarboxylation. The assay reaction mixtures are incubated for 1 week at pH 7.0, 25°C | Homo sapiens | ? | - |
? |
Subunits | Comment | Organism |
---|---|---|
monomer | 1 * 112730, mass spectrometry | Homo sapiens |
More | recombinant human GLDC is active in the monomeric form, unlike GLDC orthologues in chicken and Synechocystis where the enzyme exists as a homodimer | Homo sapiens |
Synonyms | Comment | Organism |
---|---|---|
GLDC | - |
Homo sapiens |
glycine decarboxylase | - |
Homo sapiens |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Homo sapiens |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.0001 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme | Homo sapiens | |
0.00014 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme in presence of lipoic acid | Homo sapiens | |
0.016 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme in presence of lipoylated H-protein | Homo sapiens | |
0.019 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme in presence of H-protein | Homo sapiens | |
0.031 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme | Homo sapiens | |
0.033 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme in presence of H-protein | Homo sapiens | |
0.047 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme in presence of lipoylated H-protein | Homo sapiens |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7 | - |
assay at | Homo sapiens |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
pyridoxal 5'-phosphate | - |
Homo sapiens |
General Information | Comment | Organism |
---|---|---|
physiological function | glycine decarboxylase is an unusual amino acid decarboxylase involved in tumorigenesis. In humans, GLDC is part of a multienzyme complex (which includes the lipoyl-containing H-protein) that couples the decarboxylation of glycine to the biosynthesis of serine | Homo sapiens |
kcat/KM Value [1/mMs-1] | kcat/KM Value Maximum [1/mMs-1] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.009 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme in presence of H-protein | Homo sapiens | |
0.012 | - |
glycine | pH 7.0, 25°C, recombinant individually expressed wild-type enzyme in presence of lipoylated H-protein | Homo sapiens | |
100 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme | Homo sapiens | |
150 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme in presence of lipoylated H-protein | Homo sapiens | |
890 | - |
glycine | pH 7.0, 25°C, recombinant coexpressed wild-type enzyme in presence of H-protein | Homo sapiens |