PSEUDONUCLE1NS. 177 



washed and purified by alternately dissolving in very faintly alkaline 

 water and reprecipitating with an acid, washing with water, and treating 

 with alcohol and ether. A nuclein may be prepared more simply by the 

 digestion of a nucleoprotein. In the detection of nucleins we make use 

 of the above-described method, testing for phosphorus in the product 

 after fusing with saltpeter and soda. Naturally the phosphates and 

 phosphatides must first be removed by treatment with acid, alcohol, 

 and ether, respectively. No exact methods are known for the quanti- 

 tative estimation of nucleins in organs or tissues. 



Pseudonucleins or PARANUCLEINS. These bodies are obtained as 

 an insoluble residue on the digestion of certain nucleoalbumins or phospho- 

 glycoproteins with pepsin-hydrochloric acid. Attention is called to 

 the fact that the pseudonuclein may be dissolved by the presence of too 

 much acid or by a too energetic peptic digestion. If the relation between 

 the degree of acidity and the quantity of substance is not properly selected, 

 the formation of pseudonucleins may be entirely overlooked in the 

 digestion of certain nucleoalbumins. Pseudonucleins contain phosphorus, 

 which, as shown by LIEBERMANN/ is split off as metaphosphoric acid 

 by mineral acids. 



The pseudonucleins are amorphous bodies insoluble in water, alcohol, 

 and ether, but readily soluble in dilute alkalies and barium hydroxide 

 solution. They are readily split by barium hydroxide solution with the 

 splitting off of phosphoric acid, and according to GIERTZ 2 they differ 

 in this regard from the true nucleins, which are neither dissolved nor 

 decomposed by baryta. They are not soluble in very dilute acids, and 

 may be precipitated from their solution in dilute alkalies by adding 

 acid. They give the protein reactions very strongly, but do not yield 

 purine bases. 



In preparing a pseudonuclein, dissolve the mother-substance in hydro- 

 chloric acid of 1-2 p. m., filter if necessary, add pepsin solution, and 

 allow the mixture to stand at the temperature of the body for about 

 twenty-four hours. The precipitate is filtered off, washed with water, 

 and purified by alternately dissolving in very faintly alkaline water and 

 reprecipitating with acid. 



Cleavage Products of the Nucleoproteins. 

 1. The Nucleic Acids. 



All nucleic acids are rich in phosphorus and yield phosphoric acid, 

 purine bases and a carbohydrate or carbohydrate derivative as cleavage 

 products; most of them also contain pyrimidine bases. The older 



1 Ber. d. d. chem. Gesellsch., 21, and Centralbl. f. d. med. Wissensch., 1889. 



2 Zeitschr. f. physiol. Chem., 28. 



