To efficiently remove aromatic thiols remaining together with active carbon by acidifying a reacted solution after an enzyme reaction in an aqueous solution medium containing aromatic thiols as substrates, aerating the resultant solution in the presence of active carbon and separating the solid from the solution.
In a reaction of an enzyme using aromatic thiols as substrates in an aqueous solution medium catalyzed with the enzyme such as tryptophan synthase, cysteine-desulfhydrase or methionine-γ-lyase (methioninase), after carrying out a reaction for synthesizing S-phenyl-L-cysteine from thiophenol and a β-substituted-L-alanine expressed by the formula [X is OR (R is H, an alkyl, an aryl, an aralkyl or allyl) or SR], residual aromatic thiols in the enzyme reacted solution are removed. In the removing of the thiols, the solution is acidified and aerated by the air or oxygen in the presence of active carbon, then the aromatic thiols are efficiently removed from the resultant treated solution together with the active carbon by a solid-liquid separating operation.
KOITO MITSUO
IZAWA HIDEKAZU
FUKUHARA NOBUHIRO
