406 



ANNALS NEW YORK ACADEMY OF SCIENCES 



since only there is choline acetylase found. If the esterase in all nerve 

 tissue shows a pattern so distinctly different from that of the esterases 

 of other tissues, it is justifiable to consider this enzyme as a specific 

 cholinesterase. 



HOMOGENIZED 

 ACH PR BU ME BE TR. 



HDD 



M.B. 



100 97 



22 



M400 



IIDQ 



100 101 3 31 



1 = 3.000 



IIDQ 



100 109 1 18 



1:78,000 



HDD 



100 109 26 



Figure 4. Rate of hydrolysis of different esters by the cholinesterase of the electric organ of 

 Electrophorus electricus. 



The first row gives the data obtained with a homogenized suspension of electric tissue. In such 

 suspensions, 1 mg. of protein splits about 20-40 mgs. of ACh per hour. 



The three following rows show the data obtained with increasing degrees of purity, 1 ing. of 

 protein splitting 1,400, 3,000, and 78,000 of ACh per hour, respectively. 



Of particular importance is the question of the enzyme present in the 

 electric tissue. The interpretation given for the direct proportionality 

 between voltage and enzyme activity is justified only if the enzyme is 

 exclusively, or almost exclusively, specific cholinesterase. Only in 

 that case can the proportionality be referred to as an interdependence 

 between ACh metabolism and electric manifestations. 



The enzyme extracted from the electric organ of Electrophorus elec- 

 tricus has been purified by fractional ammonium sulfate precipitation. 

 A high degree of purity may be obtained in this way. 1 milligram 

 of protein is capable of splitting twenty to thirty thousand milligrams 

 of ACh per hour. By further separation of the proteins by high speed 

 centrifugation (ultracentrifuge) , in collaboration with Dr. K. G, Stern, 

 a degree of purity has been obtained where 1 milligram of protein was 

 able to split eighty thousand milligrams of ACh per hour. If the rates 



