|
type |
Journal Article |
authors |
Tanaka, H.; Esaki, N.; Soda, K. |
title |
Properties of L-methionine gamma-lyase from Pseudomonas ovalis |
journal |
Biochemistry |
Activity |
4.4.1.11 |
Family |
4.4.1.11 |
ui |
77087734 |
year |
(1977) |
volume |
16 |
number |
1 |
pages |
100-6. |
| |
keywords |
*Carbon-Sulfur Lyases/metabolism |
abstract |
The distribution of bacterial L-methionine gamma-lyase (L-methionine methanethiollyase (deaminating) (EC 4.4.1.11) was investigated, and Pseudomonas ovalis (IFO 3738) was found to have the highest activity of enzyme, which was inducibly formed by addition of L-methionine to the medium. L-Methionine gamma-lyase, purified to homogeneity from Ps. ovalis, has a molecular weight of about 173 000 and consists of nonidentical subunits (mol wt: 40 000 and 48 000). The enzyme exhibits absorption maxima at 278 and 420 nm, and a shoulder around 330 nm, which are independent of the pH (6.0 to 10.0), and contains 4 mol of pyridoxal 5'-phosphate per mol of the enzyme. The formyl group of pyridoxal 5'-phosphate is bound in an aldimine linkage to the epsilon- amino group of lysine residues of the protein. The holoenzyme is resolved to the apoenzyme by incubation with hydroxylamine, and reconstituted by addition of pyridoxal 5'-phosphate. The enzyme activity is significantly affected by both carbonyl and sulfhydryl reagents. L-Methionine gamma-lyase catalyzes alpha,gamma- and alpha,beta-elimination reactions of, in addition to L-methionine, several derivatives of L-methionine and L-cysteine, e.g., L-ethionine, DL-methionine sulfone, L-homocysteine, and S-methyl-L-cysteine. The enzyme catalyzes also gamma-replacement reactions of the thiomethyl group of methionine with various alkanethiols (C2-C7), arylthio alcohols (benzenethiol and beta-naphthalenethiol) and the derivatives of ethanethiol (2-mercaptoethanol and cysteamine) to yield the corresponding S-substituted homocysteine. The thiomethyl group of S- methyl-L-cysteine also is replaced by ethanethiol to form S-ethyl-L- cysteine. |
last changed |
2008/06/09 17:52 |
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