Studies on the biosynthesis of epothilones: The biosynthetic origin of thecarbon skeleton

The biosynthetic origin of the epothilone skeleton was studied by the incor poration of C-13 and radioactively labeled precursors by Sorangium cellulos um So ce90. The carbon atoms are derived from acetate, propionate, the meth yl group of S-adenosyl-methionine, and cysteine which also introduces the s ulfur and nitrogen atoms. Epothilone biosynthesis starts with the formation of the thiazole part from acetate and cysteine. The incorporation of aceta te or propionate units results in the formation of epothilones A and B, res pectively. To introduce the epoxide function of epothilones A and B molecul ar oxygen is used.