%0 Journal Article %A CHUANG, LINDA F. %A COLLINS, E. B. %T Inhibition of Diacetyl Synthesis by Valine and the Roles of α-Ketoisovaleric Acid in the Synthesis of Diacetyl by Saccharomyces cerevisiae %D 1972 %J Microbiology, %V 72 %N 1 %P 201-210 %@ 1465-2080 %R https://doi.org/10.1099/00221287-72-1-201 %I Microbiology Society, %X SUMMARY: Valine did not inhibit the production of diacetyl from pyruvate by extracts of Saccharomyces cerevisiae that contained coenzyme A (CoA) and the co-factors necessary for forming acetyl-CoA. However, it did inhibit the production of diacetyl from glucose by a growing culture, though Ca-pantothenate, a precursor of CoA, was supplied. α-Ketoisovaleric acid enhanced the production of diacetyl from pyruvate and acetyl-CoA by extracts if mercaptoethylamine was present. Results indicate that α-ketoisovaleric acid has two roles in the synthesis of diacetyl by S. cerevisiae, a synthesis that generally requires an acidic environment, and that each is inhibited by excess valine. In addition to serving as an intermediate in the synthesis of acetyl-CoA, α-ketoisovaleric acid, which was not formed from valine by transamination at pH below 6·0, enhanced the activity of diacetyl synthetase. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-72-1-201