l62 



CHEMISTRY OF THE YEAST CELL. 



As regards the composition of the albuminoids resulting 

 from the decomposition of the nucleins, less is known than of 

 the nucleic acids with which they are combined. A. Kosskl 

 (III.) was the first to investigate yeast nuclein, and he found 

 that the albuminoid substance obtainable therefrom offered 

 greater resistance to the digestive enzymes (pepsin and trypsin) 

 than the yeast nuclein itself, since about 66 per cent, of the 

 latter, but only 3 per cent, of the former could be brought into 

 solution within twelve hours in the course of a comparative 



test. 



According to A. Kossel (II.), the yeast nucleic acid, first 



14 



or 



prepared by Altmann, has the formula C^yH^gNi^PoO^ 

 CjHggNgPgO^o. The same authority (V.) states that it is 

 decomposed by alkalis into carbohydrates and an acid, namely 

 plasmic acid, rich in phosphorus and in nitrogen. The formula 

 (Cj.^H.gNgPgOgo) ascribed to this latter acid by Kossel is 

 apparently only approximately correct, since no notice was 

 taken of the iron content (p. 47) subsequently found therein 

 by A. AscoLi (I.). Under the influence of boiling dilute mineral 

 acids, plasmic acid fui-nishes nuclein bases, together with phos- 

 phoric acid and a nitrogenous organic substance which has not 

 yet been more closely examined. A patent has been taken out 

 by K. ScHWiCKERATH (I.) for a process of purifying crude nucleic 

 acid from adherent brown mucinous substances, in view of the 

 preparation of yeast nucleic acid on a large scale. In this 

 connection, attention should also be directed to the German 

 Patent, No. 107,734, granted to the Elberfeld Farbenfabriken. 



The carbohydrates furnished by the action of boiling dilute 

 mineral acids on yeast nucleic acid (though not from plasmic 

 acid), reduce Fehling's solution, and, according to Kossel (V.), 

 probably consist of a mixture of glucose and one of the pentoses. 

 LiEBERMANN and BiTTO (I.) regarded them as an adherent con- 

 taminating admixture, of the character of the so-called yeast 

 gum. Similar carbohydrates have also been isolated from 

 various nucleins of animal origin by A. Kossel and A. Neumann 

 (IL), as also by Hammarsten (III.), Alfb. Noll (I.), and by I. 

 Bang (I). The two first-named workers, however, have also 

 shown that many nucleins contain two kinds of carbohydrates : 

 non-reducing carbohydrates present in the molecule of the 

 nucleic acid ; and reducing carbohydrates which, along with the 

 latter substance, take part in the structure of the nuclein com- 

 plex, and appear in company with nucleic acid on the decomposi- 

 tion of the main substance. 



Of the nuclein bases here in question, the first to be dis- 

 covered in the manner described above was hypoxanthin 

 (C-H^N^O), w^hich was obtained from yeast nuclein by Kossel 

 (III.) in 1879. Two years later he prepared 10 grams of this 

 base direct from pressed yeast by a method (VII.) of his own, 



