Studies on yeast metabolism. 7. Yeast carbohydrate fractions. Separation from nucleic acid, analysis, and behaviour during anaerobic fermentation

Abstract

A rapid method is described for adjusting the water content of the anthrone reagent to ensure that carbohydrate determination by the heat-of-mixing technique is carried out at an optimum temperature for the particular sugar concerned. Methods are examined for partition of yeast carbohydrate into trehalose, mannan, glycogen and glucan, and for extracting nucleic acid free from polysaccharide. By using the fractionation scheme proposed, and determining carbohydrate by the anthrone method and nucleic acid by the orcinol method, the separate fractions can be estimated to better than [plus or minus] 3%. An internal check is provided by the agreement between the sum of the carbohydrate fractions and the directly determined figure for total yeast carbohydrate. By the use of the scheme, it is shown that nitrogen assimilation restricts synthesis, during anaerobic fermentation of glucose, of the energy-reserve carbohydrates trehalose and glycogen, but not of the structural carbohydrates mannan and glucan. Carbohydrate formation is reduced also by high concentrations of phosphate, an effect which is counteracted by Mg ions.