BOD AN SKY: CHOLINESTERASE 



523 



Table 1 



Relation between Reaction Velocity of Cholinesterase Action and Acetyl- 

 choline Concentration 



In accord with Michaelis-M enten forvuda 



Enzyme source 



Investigator 



Dissociation 

 constant 



Dog serum 

 Dog serum 

 Dog serum 

 Human serum 

 Human serum 

 Cat superior 



cervical ganglion 



Goldstein^ 



Eadie^ 



Wright & Sabine* 



Click' 



Wright & Sabine* 



Click i« 



1.25 X 10-3 

 1.7 X 10-3 

 0.26 X 10-3 



1.1 X 10-3 



1.2 X 10-3 



1 X 10-3 



Inhibition at higher substrate concentrations (bell-shaped curve) 



much higher. As Mendel and Rudney^'^ have pointed out, and as will 

 be seen later, the concentration of electrolyte influences the optimal 

 concentration of substrate. 



The relation existing between reaction velocity and substrate con- 

 centration of acetylcholine may be of physiologic significance. Glick^° 

 found that, under optimal substrate conditions, pH 7.4 and 38°, 0.10 y 

 acetylcholine chloride was split per second, per milligram of cat supe- 

 rior cervical ganglion. Brown and Feldberg^** found that the concen- 

 tration of acetylcholine in the superior cervical ganglion of the cat was 



