ENZYMES CONCERNED WITH DIGESTION OF LIPIDS / 



only after the enzyme is purified 17 while, at high concentrations, the effec- 

 tiveness of the bile salts is decreased. 18 Sodium glycocholate has been 

 found to be a better activator than is sodium taurocholate. 19 - 20 Bile salts 

 can likewise accelerate the hydrolysis of soluble esters by lipase, 21 although 

 these same compounds inhibit the action of esterases. 22 



(b) Activators and Inhibitors of Pancreatic Lipase. A number of sub- 

 stances other than bile and bile salts, such as egg albumen, calcium oleate 

 and other soaps, blood serum, saponin, and alcohols are now known to 

 bring about this activation of the enzyme. Yamamoto 23 reported that 

 dicarboxylic amino acids and diamino acids, including ornithine, have a 

 notable effect in stimulating the action of pancreatic lipase on triacetin 

 and on olive oil. However, arginine was without effect in increasing li- 

 polysis of triacetin by pancreatic lipase. Histidine increases the rate of 

 splitting of olive oil by more than 100%. L-Histidine was shown to in- 

 crease the speed of hydrolysis of triacetin at a pH of 8.6 to 56%, and that of 

 tributyrin to 70%; it was without influence on the breakdown of butyl- 

 butyrate (CH 3 CH 2 CH 2 COOCH 2 CH 2 CH 2 CH 3 ). 24 l- and DL-Histidine were 

 found to be equally potent in augmenting the action of steapsin in the range 

 of 0.005 to 0.04 M. Histamine, likewise, was shown to be an activator 

 (30%) with a potency identical with that of tyrosine. 24 The action of lysine 

 in stimulating lipolysis is believed to be related to the presence of two free 

 amino groups, 23 although the free amino groups of the dicarboxylic acids have 

 little effect. While succinic and citric acid were found to be lipase stimu- 

 lants, fumaric acid (frans-COOHCH:CHCOOH) was inactive, although 

 the corresponding cis form, maleic acid, was quite active. 23 Willstatter and 

 Memmen 18 have reported that proteins inhibit the hydrolysis of tributyrin, 

 although certain amino acids and peptides were found to favor the hydroly- 

 sis of this simple triglyceride. 



Rosenheim 25 separated a coenzyme from lipase, in the absence of which 

 the enzyme was inactive. However, according to the more recent work 

 of Willstatter and co-workers, 19,20 such non-specific activating agents 

 exert their effect by affording an especially efficient adsorption environment 



17 R. Willstatter and E. Bamann, Z. physiol. Chem., 178, 17-31 (1928). 



18 R. Willstatter and F. Memmen, Z. -physiol. Chem., 129, 1-25 (1923). 



19 R. Willstatter, E. Waldschmidt-Leitz, and F. Memmen, Z. physiol. Chem., 125, 

 93-131 (1923). 



20 R. Willstatter and F. Memmen, Z. physiol. Chem., 133, 229-246 (1924). 



21 E. F. Terroine, Biochem. Z., 23, 429-462 (1910). 



22 G. M. Wishart, Biochem. J., 14, 406-417 (1920). 



23 T. Yamamoto, J. Biochem. (Japan), 38, 147-155 (1951). 



24 T. Yamamoto, /. Biochem. (Japan), 38, 277-287 (1951). 

 26 O. Rosenheim, J. Physiol., 40, xiv-xvi (1910). 



