Structural and mechanistic insights into homocysteine degradation by a mutant of methionine γ-lyase based on substrate-assisted catalysis.

ABSTRACT: Methionine γ-lyse (MGL) catalyzes the α, γ-elimination of l-methionine and its derivatives as well as the α, β-elimination of l-cysteine and its derivatives to produce α-keto acids, volatile thiols, and ammonia. The reaction mechanism of MGL has been characterized by enzymological studies using several site-directed mutants. The Pseudomonas putida MGL C116H mutant showed drastically reduced degradation activity toward methionine while retaining activity toward homocysteine. To understand the underlying mechanism and to discern the subtle differences between these substrates, we analyzed the crystal structures of the reaction intermediates. The complex formed between the C116H mutant and methionine demonstrated that a loop structure (Ala51-Asn64) in the adjacent subunit of the catalytic dim

SUBMITTER: Sato D 

PROVIDER: S-EPMC5441414 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature