Main Reaction: methyl mercaptan + ethionine >> ethyl mercaptan + methionine

Reference: PubMed ID: 5419261
Authors: Cherest H, Talbot G, Robichon-Szulmajster H
Title: Role of homocysteine synthetase in an alternate route for methionine biosynthesis in Saccharomyces cerevisiae.
Published: 1970 May

methyl mercaptan + ethionine --> ethyl mercaptan + methionine