Stereospecific hydroxylation of long chain compounds by a species of Torulopsis.

Abstract A species of yeast of the genus Torulopsis hydroxylates long chain C18 compounds and then converts them to glycosides of 17-l-hydroxy C18 fatty acids. Incubation of methyl [17-18O]hydroxyoleate with whole cells and of methyl oleate in the presence of 18O2 or H218O showed that the oxygen atom, introduced on hydroxylation, is not lost on glycoside formation and that it is derived from molecular oxygen and not from water. Esters of [18-2H3], [16,18-2H5], [17-2H2], [17-d-2H], and [17-l-2H]octadecanoates have been synthesized. On incubation of these compounds no deuterium atoms at C-16 and C-18 are removed but the 17-l-deuterium atom is lost. Unsaturated intermediates are, therefore, most probably not involved and 17-l-hydroxy acid is produced by displacement of an l-hydrogen atom (retention of configuration). The rate of formation of glycoside from l-deuterostearate was less than half of that from d-deuterostearate or from unlabeled stearate, suggesting the operation of a primary isotope effect