The pathway of the adaptive fermentation of galactose by yeast

Abstract

Dutch top yeast has been shown to produce adaptively an enzyme, named galactokinase, which catalyzes the phosphorylation of galactose by adenosine-triphosphate, forming an ester which has been identified as alpha-galactose-1-phosphate. The enzyme requires Mg++ and cysteine for full activity. Galactose-6-phosphate is not an intermediate in this reaction. The formation of an acid-stable ester from galactose has been observed occasionally with extracts of galactose-adapted yeast. There is no evidence for the accumulation of galactose-1-phosphate during the preadaptive period.