Method for producing L-methionine

A process for the preparation of L-methionine, comprising:

• (a) preparing a mixture, comprising:
• (1) dimethyl disulfide (DMDS),
• (2) a catalytic amount of an amino acid bearing a thiol group or of a thiol-group-containing peptide, wherein the amino acid bearing a thiol group or the thiol-group-containing peptide may optionally be in the form of the corresponding disulfide,
• (3) a catalytic amount of a reductase enzyme catalyzing the reaction for the reduction of a disulfide bridge of the amino acid bearing a thiol group or of the thiol-group-containing peptide,
• (4) hydrogen,
• (5) a catalytic amount of a dehydrogenase enzyme catalyzing the reaction for the reduction of hydrogen, and
• (6) a catalytic amount of a cofactor common to the reductase and the dehydrogenase,
• (b) carrying out the enzymatic reaction to form methyl mercaptan (CH3—SH),
• (c) adding a precursor of L-methionine and reacting the precursor with the methyl mercaptan formed in (b) to produce L-methionine, and
• (d) recovering and, optionally, purifying the L-methionine.