Protein Constituents of Spermatozoa 85 



On the mammalian side, bull semen has received much attention 

 from protein analysts. Zittle and O'Dell (1941«, 6) investigated the 

 nature of the sulphur in bull sperm and found that over two-thirds of 

 the 1-6% S present in lipid-free dry material is accounted for by 

 cystine and cysteine, and the remainder by methionine. Sarkar, 

 Luecke and Duncan (1947) whose results are shown in Table 10, 

 analysed separately frozen-dried bull spermatozoa (20 g. dry material 

 from 100 g. fresh washed sperm) and seminal plasma (1-4 g. dry 

 material from 100 ml.) for total nitrogen and amino acid content. 

 The amino acids were assayed by microbiological methods in protein 

 hydrolysates; however, with the exception of arginine, and to a small 

 extent leucine and tryptophan, the result of the amino acid analysis 

 failed to reflect the different physical character and physiological 

 function of proteins in spermatozoa and seminal plasma. The con- 

 spicuously high content of arginine in the spermatozoa is, of course, 

 due to the presence of this amino acid in the nucleoprotein, but even 

 in the seminal plasma the proportion of arginine exceeds consider- 

 ably that of any other amino acid, with the possible exception of 

 glutamic acid. Further data on the composition of bull sperm pro- 

 tein have been presented by Porter, Shankman and Melampy (1951) 

 who found in extensively washed, lipid-free and dried spermatozoa 

 16-7% nitrogen; m addition to the amino acids recorded previously, 

 they identified aspartic acid (5%), glycine (1-7%), proHne (3-1%), 

 serine (4-5%) and tyrosine (4-3%). 



There is but little information apart from some immunological 

 studies, on the chemical differences between the sperm proteins of 

 various species. An early attempt in this direction was made by 

 Faure-Fremiet (1913) who purified 'ascaridine', a protein peculiar 

 to the testicular tissue, and probably also to spermatozoa, of 

 Ascaris megalocephala; an interesing account of this and other 

 unusual characteristics of Ascaris sperm is given by Panijel (1951). 



Removal of the sperm mwleus from the cytoplasm 



Special techniques are required to sever the sperm-head from the 

 tail, as a preliminary to protein analysis in these two morphological 

 components of the sperm cell. Miescher, who pioneered in this field, 

 selected for his studies fish spermatozoa where a separation can be 

 accomplished relatively easily with water or dilute organic acids, 



