NUCLEOPROTEINS. 175 



In certain cases this is histone, and the combinations between nucleic 

 acid and protamines are also sometimes classified as nucleoproteins. 

 The combination between protamine and nucleic acid is, it seems, a 

 salt-like combination, and entirely different from the combination of the 

 proteins with nucleic acid in the nucleoproteins. The following facts, 

 given in connection with the nucleoproteins, do not apply to the nucleo- 

 protamines. The nucleoproteins differ not only according to the protein 

 component they contain, but also as to the nucleic acids, which vary 

 among themselves. There are essentially different nucleic acids, some 

 among which contain a pentose carbohydrate while others contain a 

 hexose carbohydrate. The nucleic acids also differ in regard to the 

 amount of purine and pyrimidine bases they contain (see below). 



The native nucleoproteins contain a variable, but not a high percentage 

 of phosphorus, which in most of the nucleoproteins investigated, ranges 

 between 0.5 and 1.6 per cent. They also regularly contain iron, and in 

 Octopodes, HENZE l has observed an iron-free nucleoprotein with 0.96 

 per cent copper. The nucleoproteins behave like w r eak acids, especially 

 those having considerable protein in the molecule. They therefore 

 give the ordinary protein reactions and behave in this regard like the 

 proteins. The nucleoproteins prepared from organs rich in cell nuclei 

 seem to be characterized by containing more phosphorus and having a 

 stronger acid character. All nucleoproteins are bodies that are insoluble 

 in water, but whose alkali combination is soluble in water. From 

 such a solution the nucleoprotein can be precipitated by acetic acid, and 

 in an excess of the acid, the precipitate dissolves with more or less 

 difficulty and in some cases not at all. It dissolves, on the contrary, in 

 very dilute hydrochloric acid. In this respect nucleoproteins are similar 

 to the nucleoalbumins and the mucin substances, but differ from these 

 two groups in that they yield purine bases on hydrolysis. According 

 to PLIMMER and SCOTT 2 the nucleoproteins differ from the nucleo-albu- 

 mins by the fact that with sodium hydroxide in 1 per cent solution the 

 nucleoalbumins split off phosphoric acid while the nucleoproteins do not. 

 The nucleoproteins give the color reactions of the proteins, but those 

 which have been investigated are dextrorotatory and not laevorotatory 

 (GAMGEE and JONES 3 ). 



The nucleoproteins are readily modified. The alkali combination 

 soluble in water suffers a decomposition on heating its solution, when 

 as neutral as possible, and coagulated protein separates while a protein 

 rich in phosphorus and poor in protein with strong acid character remains 



1 Zeitschr. f. physiol. Chem., 55. 



2 Plimmer and Scott, cited in Biochem. Centralbl., 8, p. 109. 



3 Hofmeister's Beitrage, 4. 



