304 THE PHYSIOLOGY OF REPRODUCTION 



the protamines have been shown by Kossel to have a constitution 

 so similar to that of the proteins that they are now considered to 

 represent one group of the protein substances. 



The study of the products of hydrolytic- decomposition shows that 

 while in the case of the typical proteins, such as the proteins of 

 muscle, of milk, or of the serum, the nitrogen is bound up in the 

 form of a great many different substances, e.g. tyrosine, leucine, 

 alanine, glycine, cystine, etc., of which as many as fifteen have been 

 isolated, the protamine molecule is composed of only a few constituent 

 substances. And further, while in the case of the typical proteins 

 the main bulk of the substance obtained on hydrolysis belongs to the 

 monoamino acids, the protamines are composed largely of the diamino 

 acids ; arginine, lysine, and histidine, which, from their basic nature 

 and the fact that they contain six carbon atoms, have received the 

 name " hexone-bases." 



Of these the most important one is arginine, which, on boiling 

 with baryta, is decomposed into \irea and diaminovalerianic acid 

 (ornithin), and has the structure — 



NH2 NH2 



I I 



NH=C-NH— CH2— CHs— CH2— OH— OOOH 



In salmine, for instance, eight-ninths of the nitrogen is bound up 

 as arginine, while the remainder of the nitrogen is present in the 

 form of monoamino acids, viz. serine, monoaminovalerianic acid and 

 proline, in the following proportions: 10 molecules of arginine + 2 

 molecules of serine + 2 molecules of proline + 1 molecule of amino- 

 valerianic acid. Similar relations are found to exist in the case of 

 scombrine and clupeine. In both these protamines eight-ninths of 

 the total nitrogen is present in the form of arginine, which is 

 combined with alanine and proline in the case of scombrine, and 

 with alanine, proline, serine, and aminovalerianic acid in the case 

 of clupeine. 



Since eight -ninths of the nitrogen of these three protamines is 

 present in the form of arginine, and since arginine contains four 

 nitrogen atoms, while the amino acids with which it is combined 

 contain only one nitrogen atom, it follows that in these three 

 protamines the number of arginine molecules must be twice as great 

 as the total number of monoamino acid molecules present in the 

 protamine molecule. 



The investigations of Kossel and Pringle^ have shown that 

 substances can be obtained by partial hydrolysis of these protamines, 

 the so-called " protones," which represent intermediate decomposition 



1 Kossel arid Pringle, " Uber Protamine und Histone," Zeitsch. f. physiol. 

 Chem., vol. xlix., 1906. 



