2 NUCLEUS 211 



Protein components. Not without reason, very complicated proteins 

 were presumed co be present in the nucleus but, contrary to expec- 

 tation, only fairly simple polypeptides, designated as protamines, were 

 found in the fish sperm. They are characterized by the fact that on 

 hydrolysis they produce a striking number of basic amino acids, 

 principally arginine, but also lysine, histidine and others. According 

 to KossEL (1929), the proportion of the di-amino acids (cf. Fig. 88, 

 p. 133) to the mono-amino acids, alanine, valine, leucine, etc. (ab- 

 breviated M), often amounts to 2:1. For example, in the case of the 

 mono-protamines 2 arginine: i M; in the di-protamines 2 (arginine, 

 histidine): i M; in the tri-protamines 2 (arginine, histidine, lysine): 

 I M. Often the basic compounds preponderate even more. Felix 

 (195 1) finds that in clupeine from the sperm of the herring 80% of the 

 amino acids are arginine, and that the molecular ratio of arginine to 

 phosphorus is 1:1 in these nuclei. This preponderance of the di- 

 amino acids results in polypeptide chains of strongly basic character. 

 As a further characteristic Kossel mentions that the amino acids with 

 5 C members (ornithine, proline, valine) are conspicuously pre- 

 dominant over those with 6 C atoms (for instance leucine), which are 

 typical for other proteins. Still more important is the complete absence 

 of cystine and amino dicarboxylic acids in the protamines. 



For example, the formula given in Fig. 121 is attributed to sturine 

 from the sperm of the sturgeon, which represents a tri-protamine. 

 Where processes of synthesis and the formation of organic substances 

 are concerned, Kossel (1905) is inclined to attribute special im- 

 portance to the alternating -C-N-C-N-order of the end groups of 

 the side chains of arginine and histidine, which also occurs in the 

 nitrogen-containing bases of nucleic acids. For the time being, 

 however, these facts can only be accepted as morphological statements, 

 for the functioning of such systems is still unknown. In this context 

 it is interesting to note that the polypeptide main chain represents a 

 -C-C-N-C-C- N-arrangement. 



The chains of the protamines obtained are not very long. E.g., 

 salmine, with a molecular weight between 2000 and 2500, consists of 

 only 15 to 18 amino acids (Kiesel, 1930), i.e., the polypeptide chain 

 would measure only about 60 A. Undoubtedly, however, the poly- 

 peptide chains of the nucleoproteins will be much longer in the native 

 state and will only break off into these short fragments as a result of 



