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Literature summary for 4.2.1.22 extracted from

  • Quazi, F.; Aitken, S.M.
    Characterization of the S289A,D mutants of yeast cystathionine beta-synthase (2009), Biochim. Biophys. Acta, 1794, 892-897.
    View publication on PubMed
Search for more literature for 4.2.1.22

Cloned(Commentary)

Cloned (Comment) Organism
CBS gene encoding the truncated yCBS (residues 1-353), lacking the regulatory domain, is expressed with a C-terminal, 6-His affinity tag in Escherichia coli Saccharomyces cerevisiae

Protein Variants

Protein Variants Comment Organism
S289A kcat/Km (L-serine) is reduced by 800fold compared to wild-type. Km (L-homocysteine) equal to wild-type, Km (L-serine) increased compared to wild-type. The reverse-reaction (L-cystathionine hydrolysis) shows a 1400fold reduction of kcat/Km (L-cystathionine) for mutant S289A which is dominated by a 230fold decrease in kcat. Residue S289 is essential in maintaining the properties and orientation of the pyridine ring of the pyridoxal 5'-phosphate cofactor. The reduction in activity of mutant S289A suggests that yeast CBS catalyzes the alpha, beta-elimination of L-Ser via an E1cB mechanism Saccharomyces cerevisiae
S289D mutant shows no beta-replacement activity. Fluorescence energy transfer between tryptophan residue(s) of the enzyme and the pyridoxal 5'-phosphate cofactor, observed in the wild-type enzyme and diminished in the S289A mutant, is absent in S289D Saccharomyces cerevisiae

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.14
-
 L-cystathionine reverse reaction (L-cystathionine hydrolysis), wild-type Saccharomyces cerevisiae
0.16
-
 L-homocysteine mutant S289A Saccharomyces cerevisiae
0.21
-
 L-homocysteine wild-type Saccharomyces cerevisiae
0.7
-
 L-serine wild-type Saccharomyces cerevisiae
0.9
-
 L-cystathionine reverse reaction (L-cystathionine hydrolysis), mutant S289A Saccharomyces cerevisiae
27.1
-
 L-serine mutant S289A Saccharomyces cerevisiae

Organism

Organism UniProt Comment Textmining
Saccharomyces cerevisiae
-
-
-

Purification (Commentary)

Purification (Comment) Organism
using Ni-NTA chromatography Saccharomyces cerevisiae

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
L-cysteine + L-homocysteine
-
 Saccharomyces cerevisiae L-cystathionine + H2S
-
 r
L-serine + L-homocysteine
-
 Saccharomyces cerevisiae ?
-
 r

Subunits

Subunits Comment Organism
dimer
-
 Saccharomyces cerevisiae

Synonyms

Synonyms Comment Organism
CBS
-
 Saccharomyces cerevisiae
cystathionine beta-synthase
-
 Saccharomyces cerevisiae

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
37
-
 assay at Saccharomyces cerevisiae

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.0045
-
 L-cystathionine reverse reaction (L-cystathionine hydrolysis), mutant S289A Saccharomyces cerevisiae
0.85
-
 L-serine cosubstrate: L-homocysteine, mutant S289A Saccharomyces cerevisiae
0.85
-
 L-homocysteine cosubstrate: L-serine, mutant S289A Saccharomyces cerevisiae
1.03
-
 L-cystathionine reverse reaction (L-cystathionine hydrolysis), wild-type Saccharomyces cerevisiae
17
-
 L-serine cosubstrate: L-homocysteine, wild-type Saccharomyces cerevisiae
17
-
 L-homocysteine cosubstrate: L-serine, wild-type Saccharomyces cerevisiae

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8.6
-
 assay at Saccharomyces cerevisiae

Cofactor

Cofactor Comment Organism Structure
pyridoxal 5'-phosphate
-
 Saccharomyces cerevisiae

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
0.005
-
 L-cystathionine reverse reaction (L-cystathionine hydrolysis), mutant S289A Saccharomyces cerevisiae
0.031
-
 L-serine mutant S289A Saccharomyces cerevisiae
6.3
-
 L-homocysteine mutant S289A Saccharomyces cerevisiae
7.5
-
 L-cystathionine reverse reaction (L-cystathionine hydrolysis), wild-type Saccharomyces cerevisiae
25
-
 L-serine wild-type Saccharomyces cerevisiae
80
-
 L-homocysteine wild-type Saccharomyces cerevisiae