40 Life: Its Nature and Origin 



adenine-thymine and guanine-cytosine could occur. X-ray photo- 

 graphs of purified material led to the final postulate that this 

 ladder-like double chain is actually coiled into a helix, one com- 

 plete circle to about every ten sugar groups. The molecular weight 

 has been estimated at 800,000. 



The protamines are proteins peculiar to nuclei, with calculated 

 molecular weights ranging from 2,000 to 12,000. Each protamine 

 molecule contains eight or ten kinds of amino acids of a select 

 known group of about 12, of which proline, alanine, and arginine 

 are common. The proportions of the various amino acids and the 

 exact order of their arrangement varies from species to species. 

 Felix (1955) indicated that, according to present knowledge, there 

 are possibilities in these molecules for the existence of literally mil- 

 lions of different compounds. Felix calculated that in the nucleus 

 there are about 100 protamine molecules per molecule of DNA, and 

 he suggested that protamine and DNA are actually combined in 

 this ratio of 100:1 to form enormous nucleoprotamine molecules. 

 He further calculated that each trout sperm nucleus has space for 

 about 4,660,000 of these nucleoprotamine molecules, which would 

 be an average of 233,000 per chromosome. Other investigators 

 believe that the DNA and protamines are not actually combined 

 chemically but lie together in some fashion (Kacser, 1956; Serra, 

 1958). Serra pointed out that the protamines form the main back- 

 bone of the chromosome strands, that the DNA is distributed un- 

 evenly along it or among its strands (Fig. 18), and that DNA, at 

 least in the form identified by current techniques, may be greatly 

 reduced in quantity during the growing stages of the cell. 



The duplication of the giant nucleoprotein structures is poorly 

 understood. Many models have been proposed for the synthesis of 

 the duplicate member (Crick, 1954; Kacser, 1956; Steinberg, 

 Vaughan, and Anfinsen, 1956; Taylor, Woods, and Hughes, 1957; 

 Hoagland, 1959). However, the relationship between RNA, DNA, 

 and protamines has not yet been established. Serra (1958) em- 

 phasized that synthesis of the protamine must precede synthesis of 

 new DNA and concluded that none of these compounds re- 

 duplicate themselves directly but that one is formed by the other. 



Although the exact processes are still obscure, enough is known 

 about them to suggest that final duplication at cell maturity of 

 RNA, DNA, and the protamines is in some fashion associated with 

 the climactic molecular machines which trigger the reactions lead- 

 ing to cell division (Burns, 1959) and that the products of this 



