Abstract
Sulfur source in the biosynthesis of biotin from desthiobietin by washed cells of Saccharomyces cerevisiae which were deficient in biotin, or in biotin and sulfur was investigated, and it was elucidated that methionine acted an important role. In the case of biotin-and sulfur-deficient cells, biotin was produced in better yield in the procedure carried out by the addition of glucose and desthiobiotin after preincubation with glucose and sulfur compounds, than the procedure carried out by the addition of glucose, desthiobiotin and sulfur compounds without preincubation. The most effective sulfur compounds were methionine sulfoxide and methionine, followed by Na_2SO_4,Na_2SO_3 and Na_2S. Cysteine, cystine and methionine sulfone were less effective. In the case of Na_2SO_4,the further addition of glucose in combination with desthiobiotin was necessary after preincubation, but not necessary in the case of methionine. The biosynthesis of biotin by biotin-deficient cells was inhibited by ethionine and reversed only by methionine.
