OXIDATIVE AND BIOSYNTHETIC REACTIONS 91 



Table III. Effect of DNP on anaerobic metabolism of pyruvate in bull 

 spermatozoa 



Additions 



c»o 2 



(jul/10 8 spermatozoa/hr) 



None 9.9 



DNP 4.6 



Fluoride 9.9 



Fluoride, DNP 4.2 



a Washed spermatozoa incubated in phosphate saline at 37°; gas, 100% N 2 . 1-C 14 - 

 pyruvate, 0.005Af in all vessels; DNP, 10" 4 A/; fluoride, 0.023/; incubation period, 60 

 min; sperm count, 19.89 X 10 8 /vessel. 



washed spermatozoa led to the conclusion that bull spermatozoa con- 

 tain a powerful enzyme system which catalyzes the dismutation be- 

 tween two molecules of pyruvate, analogous to the reaction studied 

 in bacterial extracts by Korkes et al. (1951): 



2CH 3 CO COOH + CoASH -* 



CH3CO S CoA + CH3CHOH COOH + CO, 



This reaction would account for the reduction of pyruvate to lactate 

 in the absence of carbohydrate under both aerobic and anaerobic 

 conditions. It can be followed by measuring the amount of radio- 

 active CO., evolved from l-C 14 -pyruvate by a sperm suspension incu- 

 bated under strictly anaerobic conditions. As can be seen from Table 

 III, the anaerobic decarboxylation of pyruvate is also inhibited by 

 DNP (Terner, 1959). 



What is the significance of the dismutation reaction of pyruvate 

 in bull spermatozoa? It might be argued that a study of the metabo- 

 lism of pyruvate is only of academic interest since the physiological 

 substrate is carbohydrate and, in particular, fructose. And it is gen- 

 erally assumed that bull spermatozoa can obtain all the energy for 

 the maintenance of motility from anaerobic glycolysis. That would 

 make a study of the fate of pyruvate, other than its reduction to lac- 

 tate in the course of glycolysis, relatively unimportant. For it may 

 be expected that in the presence of carbohydrate the dismutation be- 

 tween two molecules of pyruvate will be suppressed, giving way to 

 the better known and more important oxidation-reduction step of 

 glycolysis. 



