Abstract
1. The cells cultured in the desthiobiotin-limitting and sulfur-deficient medium showed the marked ability of biotin formation from desthiobiotin and various sulfur sources.
2. The most effective sulfur compounds were metionine sulfoxide and methionine, followed by sodium sulfide, sodium, sulfite, sodium sulfate, homocysteine, S-adenosylmethionine, and methylmercaptan. Cysteine, cystine, methionine sulfone, 5′-methyladenosine, choline sulfate and glutathione were less effective. In the case of sodium sulfate, further addition of glucose in combination with desthiobiotin was necessary after preincubation, but not necessary in the case of methionine.
3. Biotin formation by biotin-deficient cell suspension was inhibited by ethionine and was restored only by addition of methionine.
