84 The Biochemistry of Semen 



a result of extensive washing. However, even if the separation of 

 sperm from the seminal plasma has been carried out with due care 

 and attention, there is no certainty that a loss of intracellular pro- 

 tein has not been incurred. For this reason, one cannot but view 

 with suspicion the results of protein analyses in sperm, if they have 

 been performed with spermatozoa centrifuged at high speed, or 

 washed extensively with large volumes of diluents, some of them 

 anisotonic or unbuffered. 



The data at present available indicate that spermatozoa have 

 a much higher concentration of proteins than the seminal plasma. 

 Friedrich Miescher (1870, 1878, 1897) whose fundamental studies 

 provided the earliest information on the chemical nature of some 

 of the sperm proteins, was also the first to point out that in salmon, 

 for instance, the high dry weight and protein content of semen was 

 almost entirely due to the spermatozoa, whereas the seminal plasma 

 gave practically no precipitate with 2 vol. of acidified ethanol, and 

 contained no more than 0-78% dry matter, of this 0-65% mineral, 

 and only 013% organic, material. However, a more recent analysis 

 of Sabno fontinalis has shown a content of 1 -76% nitrogen and 

 0-43% phosphorus in the seminal plasma (Felix, Fischer, Krekels 

 and Mohr, 1951). Sea-urchin {Arbacla punctulata) seminal plasma 

 has about 0-25% protein (Hayashi, 1945). 



Table 10. Protein composition of bull semen 

 (Sarkar et al, 1947) 



In dried material, ash and lipid-free 

 (mg./lOOg.) 



