156 



The Biochemistry of Semen 



The activity of hexokinase, the enzyme which brings about the 

 initial reaction between ATP and glycolysable sugar, can be demon- 

 strated directly in washed spermatozoa (Mann, 1945/)). If we add 

 to a ram sperm suspension sugar (glucose, fructose or mannose), 



Fig. 15. Diagrammatic representation offructolysis in semen. 



sodium fluoride, and ATP, there is on incubation a rapid disap- 

 pearance of half of the readily-hydrolysable phosphorus of ATP 

 and formation of adenosinediphosphate (ADP) and 6-phospho- 

 hexose. Of course, without added ATP and fluoride, 6-phospho- 

 hexose does not accumulate but the degradation of sugar continues 

 uninterruptedly to its final stage, i.e. the formation of lactic acid. 



