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Literature summary extracted from

  • Chen, X.; Wang, L.; Fazlieva, R.; Kruger, W.D.
    Contrasting behaviors of mutant cystathionine beta-synthase enzymes associated with pyridoxine response (2006), Hum. Mutat., 27, 474-482.
    View publication on PubMed

Cloned(Commentary)

EC Number Cloned (Comment) Organism
4.2.1.22 expression in Escherichia coli Homo sapiens

Protein Variants

EC Number Protein Variants Comment Organism
4.2.1.22 I278T 1-5% of the specific activity of the wild-type enzyme. Decreased activity is due to reduced turnover rate and not substrate binding. Mutant enzyme does not have altered affinity for 5'-pyridoxal phosphate. KM-value for pyridoxal 5'-phosphate is 1.4fold lower than wild-type value. KM-value for L-serine is 1.2fold lower than wild-type value. KM-value for L-homocysteine is 3.6fold higher than wild-type value. KM-value for L-cysteine is 1.7 fold lower than wild-type value Homo sapiens
4.2.1.22 R266K 30-100% of the specific activity of the wild-type enzyme. Decreased activity is due to reduced turnover rate and not substrate binding. Reduced affinity for 5'-pyridoxal phosphate compared to the wild type enzyme. KM-value for pyridoxal 5'-phosphate is 2.9fold higher than wild-type value. KM-value for L-serine is 1.6fold lower than wild-type value. KM-value for L-homocysteine is identical to wild-type value. KM-value for L-cysteine is 1.4 fold lower than wild-type value Homo sapiens

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
4.2.1.22 1.41
-
 L-serine 37°C, pH 8.6, mutant enzyme I278T Homo sapiens
4.2.1.22 1.74
-
 L-serine 37°C, pH 8.6, wild-type enzyme Homo sapiens
4.2.1.22 2
-
 homocysteine 37°C, pH 8.6, mutant enzyme I278T Homo sapiens
4.2.1.22 2.76
-
 L-serine 37°C, pH 8.6, mutant enzyme R266K Homo sapiens
4.2.1.22 3.59
-
 L-cysteine 37°C, pH 8.6, mutant enzyme I278T Homo sapiens
4.2.1.22 4.3
-
 L-cysteine 37°C, pH 8.6, mutant enzyme R266K Homo sapiens
4.2.1.22 6.11
-
 L-cysteine 37°C, pH 8.6, wild-type enzyme Homo sapiens
4.2.1.22 7.17
-
 homocysteine 37°C, pH 8.6, mutant enzyme R266K Homo sapiens
4.2.1.22 7.17
-
 homocysteine 37°C, pH 8.6, wild-type enzyme Homo sapiens

Organism

EC Number Organism UniProt Comment Textmining
4.2.1.22 Homo sapiens
-
-
-

Purification (Commentary)

EC Number Purification (Comment) Organism
4.2.1.22
-
 Homo sapiens

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
4.2.1.22 L-serine + L-cysteine
-
 Homo sapiens ?
-
 ?
4.2.1.22 L-serine + L-homocysteine
-
 Homo sapiens cystathionine + H2O
-
 ?

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
4.2.1.22 0.031 0.51 L-homocysteine 37°C, pH 8.6, wild-type enzyme Homo sapiens
4.2.1.22 0.04 1.97 L-homocysteine 37°C, pH 8.6, mutant enzyme R266K Homo sapiens
4.2.1.22 0.04
-
 L-cysteine 37°C, pH 8.6, mutant enzyme I278T Homo sapiens
4.2.1.22 0.052 2.1 L-serine 37°C, pH 8.6, wild-type enzyme Homo sapiens
4.2.1.22 0.09
-
 L-homocysteine 37°C, pH 8.6, mutant enzyme I278T Homo sapiens
4.2.1.22 0.15
-
 L-serine 37°C, pH 8.6, mutant enzyme I278T Homo sapiens
4.2.1.22 1.95
-
 L-cysteine 37°C, pH 8.6, mutant enzyme R266K Homo sapiens
4.2.1.22 2.9
-
 L-serine 37°C, pH 8.6, mutant enzyme R266K Homo sapiens
4.2.1.22 3.13
-
 L-cysteine 37°C, pH 8.6, wild-type enzyme Homo sapiens
4.2.1.22 4.39
-
 L-cysteine 37°C, pH 8.6, wild-type enzyme Homo sapiens
4.2.1.22 7.93
-
 L-homocysteine 37°C, pH 8.6, wild-type enzyme Homo sapiens
4.2.1.22 9.06
-
 L-homocysteine 37°C, pH 8.6, mutant enzyme R266K Homo sapiens
4.2.1.22 10.19
-
 L-serine 37°C, pH 8.6, wild-type enzyme Homo sapiens

Cofactor

EC Number Cofactor Comment Organism Structure
4.2.1.22 pyridoxal 5'-phosphate Km-value for wild-type enzyme: 0.00118 mM, KM-value for mutant enzyme I278T: 0.00084 mM, KM-value for mutant enzyme R266K: 0.00339 mM Homo sapiens