Phosphorylation in living yeast

Abstract

At the onset of fermentation of sugar by fresh brewery yeast the acid-soluble orthophosphate content of the cells falls to a fairly constant value and regains the original level when fermentation ceases. This is evidence that phosphorylation is concerned in the glycolytic process of the yeast cell. The coincident changes in total, labile and organic (acid-soluble) phosphate could not be consistently related to the fermentation process. Nothing is known of the nature of the compound formed by the disappearing orthophosphate, but the P balance suggests that it may be acid-insoluble. A process is descr. by which different P compounds can be successively extracted from fresh yeast. Metaphos-phoric acid has been shown to be present in the tri-chloracetic acid ext., but neither hexosedi- nor hexose-mono-phosphoric ester has been identified. Approx. 30% of the total P of yeast is present as a complex containing Fe, nucleic acid, and metaphosphoric acid. By extraction of the nucleic acid complex with HC1, inorganic metaphosphate was obtained. The nucleic acid complex is probably identical with the "Plasminsaure" descr. by Kossel. During the autofermentation of yeast in the presence of toluene the metaphosphoric acid present in the nucleic acid fraction was decomposed, with the ultimate production of orthophosphate.