CXXV.—Glycogen from yeast

Abstract

THE occurrence in the yeast cell of a substance which yields a reddishbrown coloration with iodine appears to have been first observed by Errera in 1882 (L'EpipZasnze dcs Ascomyc8te.s et Ze Glycogdne des vgqgttaux, Bruxelles, 1885, and Compt. Tend., 1885, 101, 253), although the existence of a carbohydrate reserve substance had been surmised by Pasteur in 1859. On account of this reaction, it was considered to be glycogen, and Errera attempted to extract it from the cell, but did not succeed in obtaining it sufficiently pure t o be certain of its identity with ordinary glycogen.It was next examined by Cremer (Munchener Med. Wochenschr., 1894, 41, 525), who stated that he prepared it from yeast and purified it by Briicke's method (precipitation of the proteids by potassium mercuriiodide) and by fractional precipitation, 13 grams being obtained from 250 grams of dried yeast. He describes it as a neutral white powder, of specific rotation [ a ID + 198.9". It gave a red coloration with iodine, formed a n opalescent solution in water, was converted by boiling with 1225 dilute hydrochloric acid into dextrose, and was inverted by saliva, pancreatic juice, and diastase, A much more detailed investigation on this subject was made by Clautriau (Etude chirnique du Glycogdne. Mem. Coummgs, Acud. Roy. Belg., 1895, 53), who prepared glycogen from yeast, from two species of fungi, and from the rabbit, and carefully compared their properties. Clautriau made use of yeast which had been enriched in glycogen by treatment with wort containing 1 2 per cent. of cane-sugar, and after repeatedly boiling it with ' 1 per cent. aqueous potash and washing with water disintegrated the cells by making them into a solid mass with silica, chalk, and potassium silicate, and then grinding the whole to a fine powder. The glycogen was then extracted by boiling water, a,nd was freed from mucilaginous matters by the repeated production in its solution of a precipitate of calcium phosphate, the last traces of gum being removed by saturating the solution with salt and then adding ammonium sulphate in excess. The glycogen was precipitated from the diluted solution by an excess of iodine, the precipitate treated with sulphurous acid, and the glycogen precipitated by the addition of two volumes of alcohol, and finally washed with absolute alcohol and ether and dried in the air. He thus obtained it free from nitrogen, but containing 1-3-15 per cent. of ash, and observed that in its general properties it agreed with the substance described by Cremer.

Biochemistry, Pharmacology, and Physiological Chemistry of Phosphates

“…The important role which phosphate plays in fermentation was shown by Harden andYoung in 1905 and1906.2 They demonstrated that orthophosphate disappeared and was rate-limiting during fermentation. They also showed that the orthophosphate which disappeared was incorporated or fixed as the phosphate ester fructofuranose-1,6-diphosphate.…”

“…Emphasis will be on (1) the role of orthophosphate as an initiator of the reaction sequence, (2) the specific reactions in which adenosine triphosphate is utilized to make them exergonic, and (3) the generation of adenosine triphosphate at the expense of the oxidation of pyridine nucleotide coenzyme.…”

“…In equation (2), glycogen undergoes phosphatolysis by the orthophosphate anion in the presence of the enzyme phosphorylase. The 1 ,4-linkage between glucose residues in glycogen is ruptured with the formation of glucose-i-phosplhate.…”

“…The result is the resynthesis of coenzyme plus the formation of glucose-6phosphate. The reaction is reversible but the equilibrium is in favor of the forward direction as written in equation (2).…”

Observations on the Glycogen Content of Certain Invertebrates and Fishes

“…As much as 2 per cent. of glycogen, apparently identical with that prepared from rabbit liver and from oysters, was isolated by Harden and Young (8) from washed pressed yeast.…”