CHAPTER V 



Protein Constituents and Enzymes 

 of the Seminal Plasma 



Proteoses and free amino acids. Fibrinolysin and fibrinogenase. Pepsino- 

 gen. Ammonia formation. Amino acid oxidase. Seminal phosphatases; 

 *acid' and 'alkaline' phosphatase; 5-nucleotidase; pyrophosphatase. 

 Enzymic hydrolysis of adenosine triphosphate. 



Proteoses and free amino acids 



A DISCUSSION of the nature of extracellular protein constituents of 

 semen demands the recognition of certain circumstances which are 

 peculiar to the seminal plasma. An important, though sadly ne- 

 glected fact is that the protein content of the seminal plasma does 

 not remain constant after ejaculation but undergoes rapid changes 

 of enzymic character which manifest themselves in a progressive 

 decrease in the concentration of non-dialysable protein-nitrogen 

 and a simultaneous accumulation of non-protein nitrogen, free 

 amino acids and, at a late stage, of free ammonia. Unless this is 

 fully taken into account, results of protein and amino acid analysis 

 in semen are but of little significance and yield no information on the 

 initial distribution of nitrogenous compounds. This applies especi- 

 ally to human semen as was convincingly demonstrated by Lund- 

 quist (1949c, 1952), and also by Jacobsson (1950, Fig. 11). 



Even in freshly collected seminal plasma a large proportion of 

 total nitrogen is found partly as a protein-like material which passes 

 readily through semi-permeable membranes but is not heat-coagu- 

 lable and not precipitated by trichloroacetic acid; accordingly, this 

 has been classified as propeptone, hemialbumose, primary proteose, 

 and secondary proteose (thioalbumose and synalbumose) (Posner, 

 1888, 1892; Marshall, 1922; Goldblatt, 1935^). In human semmal 

 plasma, out of a total content of about 3-5 to 5-5 g. protein-like 

 material per 100 ml., no more than 18%, usually much less, is 

 coagulated by heat, and about 60% passes through cellulose 



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