ENZYMES CONCERNED WITH DIGESTION OF LIPIDS 37 



Table 4 



Inhibition, by Certain Drugs, of Cholinesterases Prepared from Serum, 



Erythrocytes, and Brain of Man" 



Percent inhibition of cholinesterase 



Inhibitors Brain 



cholin- 



Compound Concn., M a-Type e-Type esterase 



Percaine (Nupercaine) 6 0.006 94 25 12 



Irgamide* 0.006 46 4 3 



4-Isopropylantipyrine . 002 65 IX 



Morphine 0.006 m 76 66 



(satd.) 



Caffeine 0.006 4 42 40 



• Data from A. E. Zeller and A. Bissegger, Helv. Chim. Acta, 26, 1619-1630 (1943). 



6 2-Butoxy-A r (2-diethylaminoethyl )-cinchoninamide hydrochloride. 



c A'-Dimethylacroyl-p-aminobenzenesulfonamide (A'-senecioylsulfanilamide). 



Table 5 

 The Inhibition of Cholinesterases by Different Inhibitors 



e-Type s-Type 



cholin- cholin- 



Inhibitor esterase esterase 



Pyrazolones"' 6 C + 



Local anesthetics (percaine)"" 1 C + 



Sulfonamides"''"'-'' C + 



Methylhydroxy purines - 4 + 



Triorthocresyl phosphate" C + 



Diisopropyl fiuorophosphate* C + 



Dimethylcarbamate of (2-hydroxy-5-phenyl- 



benzyl)trimethylammonium bromide 1 '' C -f 



Antipyrine* + 



° E. A. Zeller and A. Bissegger, Helv. Chim. Acta, 26, 1619-1630 (1943). 



b E. A. Zeller, Helv. Chim. Acta, 25, 1099-1 1 10 (1942). 



r This represents a markedly lower sensitivity as compared with the other type. 



d D. Nachmansohn and H. Schheemann, ./. Biol. Chem., 159, 239-240 (1945). 



' K. A. Zeller, Helv. Chim. Acta, 25, 216-229 (1942). 



t E. A. Zeller, Verhandl. Ver. schweiz. Phi/siol, 19, 35-36 (1941). 



B. Mendel and H. Rudnev, Science, 100, 499-500 (1944). 



>• It. D. Hawkins and B. Mendel, Brit. J. Pharmacol, 2, 173-180 (1947). 



1 R. D. Hawkins and J. M. Gunter, Biochem. J., 40, 192-197 (1946). 



i R. D. Hawkins and B. Mendel, /. Cellular Comp. Physiol., 27, 69-85 (1946). 

 k E. A. Zeller, Verh. Ver. schweiz. Physiol, 20, 51-52 (1942). 



acetylcholine for the enzyme surface. 223 Urethanes related to eserine 

 (physostigmine) and prostigmine also inhibit competitively, but these 

 also combine with and dissociate from the enzyme extraordinarily slowly, 

 so that competitive displacement by substrate is also very slow. Gold- 



223 A. Goldstein, Arch. Biochem., 84, 169-188 (1951). 



