1909. i 



Yeast-juice from Hexose and Phosphate. 



529 



In a paper on the changes that take place in the phosphorus compounds of 

 plants, etc.,* Iwanoff stated that, during the fermentation of sugar by pressed 

 yeast, the inorganic phosphates of the yeast are converted into organic 

 compounds. This observation, however, remained unknown to the author of 

 the present paper until the publication of a later paper by Iwanoff,f in which 

 he described the formation of a phosphoric acid compound during the fermen- 

 tation of glucose or fructose in the presence of sodium phosphate by yeast 

 which had been previously treated with acetone (" zymin "). By precipitating 

 with copper acetate, decomposing with sulphuretted hydrogen and evaporating, 

 he obtained the free acids, corresponding to these compounds, in the form of 

 dark brown syrups, which when prepared from glucose contained 19'6 to 

 20 per cent., and from fructose 13"4 to 14 per cent., of phosphorus. No other 

 analyses were given in the paper. These syrups gave the characteristic 

 reactions of aldo- and keto-groups, and yielded osazones when heated with 

 phenylhydrazine, that from the glucose compound melting at 142°, and that 

 from the fructose compound at 125°. Iwanoff concluded that these bodies 

 were compounds of phosphoric acid either with a triose or with methylglyoxal, 

 .and that they were different according to the sugar from which they were 

 derived. 



At the time when Iwanoff s paper appeared, a considerable amount of work 

 had been done by the author on this reaction, and a preliminary note was 

 published describing the isolation of the compound by means of its lead salt.J 

 It was shown that this salt had the empirical formula C3H 5 02(P0 4 Pb), and 

 when decomposed with sulphuretted hydrogen yielded an acid which was 

 slightly dextro-rotatory, and which, when the solution was boiled, underwent 

 hydrolysis with formation of phosphoric acid and a ltevorotatory reducing 

 substance. 



The present paper embodies the results of further work on this substance, 

 and also on the similar compounds obtained by fermenting fructose and 

 mannose in place of glucose. No difference has been detected between the 

 compounds obtained from these three sugars. 



Preparation of the Lead Compound. — A solution of 0'6 molar di-sodium or 

 potassium hydrogen phosphate (E^HPCXi) was added to a mixture of yeast- 

 juice and excess of glucose at 25°, in such an amount that rapid fermentation 

 was set up. The quantity of phosphate which may be used varies with 

 different juices,§ and the necessary amount was determined in each case in 



* 'Travaux de la Societe des Naturalistes de St. Petersbourg,' vol. 34, 1905. 



t 'Zeit. physioL Chem.,' 1907, vol. 50, p. 281. 



% Young, ' Chem. Soc. Proc.,' 1907, vol. 23, p. 65. 



§ Harden and Young, ' Koy. Soc. Proc.,' B, 1908, vol. 80, p. 299. 



