Aspergillus nigerによるBiotinの³⁵S標識化の試み

抄録

Labeling of biotin with sulfur-35 was carried out in a medium containing Aspergillus niger with 4.5mCi of H₂³⁵SO₄ and dethiobiotin. A large amount of ³⁵S-amino acid besides ³⁵S-biotin and its related compounds (biotin fraction) were obtained. Following amino acids were identified by a two-dimensional paper chromatography : ³⁵S-Cysteinic acid, ³⁵S-cystine, ³⁵S-homocystine, ³⁵S-methionine, ³⁵S-methionine sulfoxide, and ³⁵S-methionine sulfone. About one-half of the added ³⁵S (46%) remained in the supernatant as non-reacted H₂³⁵SO₄ and or non-hydrolysed proteins, and a greater amount (89%) of radioactvities taken up by the cell were incorporated into ³⁵S-amino acids. In the biotin fraction, 0.7% of the total radioactivity was found. Biotin fraction was isolated as avidin complex, dialysed with ammonium carbonate, and identified chromatographically from radioactivity and by bioassay. From this experiment, biotin was found mainly in an oxidized form such as l-sulfoxide and l-sulfone.