Method of producing sulfur containing L-amino acids

A method for the production of substituted sulfur-containing L-amino acids in which the sulfur is attached to the .beta.- or .gamma.-carbon atom of the amino acid, which comprises:

• a. contacting a .beta.- or .gamma.-substituted L-amino acid in an aqueous reaction medium containing methioninase together with a sulfur containing compound to accumulate the substituted sulfur-containing L-amino acid in the medium, and
• b. recovering the substituted sulfur-containing L-amino acid from the medium, the said .beta.- or .gamma.-substituted L-amino acid being characterized as one which is converted to pyruvic or .alpha.-keto butyric acid when held in an aqueous medium with methioninase, the said sulfur-containing compound being characterized as one which contains an active hydrogen atom and at least one unshared electron pair associated with the sulfur atom, the substituted sulfur-containing L-amino acid being characterized as one in which the original .beta.- or .gamma.-substitute is replaced by the entire nucleophilic moiety of the sulfur-containing compound which remains after removal of hydrogen therefrom.