ATPASE AND ACETYLCHOLI M s TERASE OF SPERM 



239 



hibition occurs at concentrations which are far too low to chelate all 

 the magnesium in the system (Perry and Grey, 1956). The effect of 

 pyrophosphate and EDTA on the sperm tail enzyme was determined. 

 At concentrations of magnesium ions comparable to or less than the 

 pyrophosphate concentration, some inhibition occurred, but EDTA 

 was a far more effective inhibitor, and further experiments were con- 

 fined to the use of this substance. 



Enzyme measurements and the subsequent work on changes in fla- 

 gellar volume were all carried out in pH 7.8, 0.05AI tris buffer con- 

 taining 0.5AI sucrose. The flagella themselves were isolated in this 

 medium from milt diluted with the same tris buffer containing both 

 0.5M sucrose and 2.5 mM EDTA. Although this medium seemed to 

 permit a reasonably high degree of morphological integrity, no claim 

 is made that it is the most suitable for the purpose. 



Figure 2 shows the effect of EDTA on the perch sperm ATPase, the 

 EDTA being added prior to the magnesium activator to indicate the 



I 2 3 4 5 6 



CONCENTRATION OF Nlg + +(mM) 



Effect of Mg+ + activator on the sperm tail ATPase in the pres- 

 ^^•TA. Incubation at 37° for 10 min in pH 7.8, 0.05M tris buffer 

 containing O.bM sucrose and 2 mM ATP. Q, no EDTA; A> 1-25 mM 

 EDTA; □, 2.5 mM EDTA. 



Fig. 2. 

 ence of EDTA 



