2‘-Hydroxypyridoxol, a Biosynthetic Precursor of Vitamins B6 and B1 in Yeast

In separate experiments cultures of the yeast Saccharomyces cerevisiae ATTC 7752 were grown in the presence of [5',5'-2H2]- or of [2',2',5',5'-2H4]-3-hydroxy-2,4,5-tri(hydroxymethyl)pyridine (i.e., 2'-hydroxypyridoxol). The 2H NMR spectra of the samples of pyridoxamine dihydrochloride and of thiamin chloride hydrochloride that were isolated from the two experiments showed the presence of deuterium at the corresponding sites. Entry of deuterium from the specifically 2H-labeled samples of 2'-hydroxypyridoxol into the predicted sites of pyridoxamine and of the pyrimidine unit of thiamin provides the first unequivocal evidence that, in yeast, 2'-hydroxypyridoxol is an intermediate on the route from a C5-sugar into vitamin B6, and adds to the evidence that pyridoxol serves as a precursor of the pyrimidine unit of thiamin, supplying the C5N unit, C-2',2,N-1,C-6,5,5' as an intact unit.