STUDIES ON THE FORMAION OF BIOTIN FROM DESTHIOBIOTIN AND SULFATE IN SACCHAROMYCES CEREVISIAE

III. ISOTOPIC STUDIES ON BIOTIN FORMATION FROM DESTHIORIOTIN AND S³⁵-LABELLED SULFATE BY WASHED CELL SUSPENSION OF YEAST

Abstract

1. The biosynthesis of biotin-S³⁵ from H₂S³⁵O₄ and desthiobiotin by the washed cell suspension of biotin and sulfur-deficient Saccharomyces cerevisiae was investigated with the following two methods.
2. The biotin and sulfur-deficient cell suspension was incubated with sulfate-S³⁵ and D-glucose, and the fate of sulfate-S³⁵ was investigated. L-Methionine-S³⁵ was found to be produced predominantly.
3. The experiments with L-methionine-S³⁵ and desthiobiotin showed the formation of biotin-S³⁵ in a good yield.
4. Using 140μc of L-methionine-S³⁵, 0.26μc of biotin-S³⁵ was obtained by the biotin-avidin complex method, followed by autoradiography, bioautography and paper chromatoscanning.
5. From these findings, it is concluded that 70 per cent of the radioactivity in the biotin concentrate is located in biotin-related compounds, i.e., biotin-D-sulfoxide, biotin-L-sulfoxide, biocytin and biocytin sulfoxide.