| abstract |
L-Cysteine and/or L-cystine may be prepared by reacting a beta -substituted L-alanine represented by the general formula (I): <IMAGE> wherein X is a halogen atom, or an -OR or -SR group where R is a hydrogen atom, or an alkyl, acetyl, benzyl or sulfonic acid group, with a metal sulfide, a metal hydrosulfide, a metal polysulfide, ammonium sulfide, ammonium hydrosulfide or an ammonium polysulfide in the presence of tryptophan synthase. |