ATPASE AND ACETYLCHOLINESTERASE OF SPERM 



243 



300 n 



LOG. 



t 1 r 



4 3 2 



SALT CONCENTRATION (M) 



00 



Fig. 5. Effect of added salt on ATPase activity of perch sperm tails in 

 absence of EDTA. Incubation at 37° for 10 min in pH 7.8, 0.05^/ tris buffer 

 containing 0.5Af sucrose, 2 mM ATP and 2.5 mM MgCl 2 . Q, NaCl; A, 



NaCN; fj, NaF. 



well known for the ease with which they split into their component 

 fibrils. 



Several attempts were made to reverse the effect by adding excess 

 EDTA to preparations in which the optical density change, taking 

 place on addition of ATP and activator, had just been determined. 

 These attempts were without success. 



The general results indicate a reduction in optical density of some 

 15% usually occurs when the inhibited ATPase of perch sperm tail 

 preparations is activated in the presence of substrate. Apparently 

 ATP can only be replaced by ADP and the magnesium activator, to 



