ENZYMES CONCERNED WITH DIGESTION OF LIPIDS 65 



thesis and neuromuscular function. Administration of ACTH increased the 

 ability of the brain of non-operated as well as of hypophysectomized rats 

 to synthesize acetylcholine. These workers 379 suggest that the pituitary 

 gland functions in maintaining the amplitude of the action potential in the 

 nerve unaltered for a period of time during repeated stimulation; it also 

 brings about an optimal acetylcholine synthesis by the release of ACTH. 

 Neither cortisone nor compound F (17-hydroxycorticosterone-21-acetate) 

 was found to duplicate fully the effects of ACTH on acetylcholine syn- 

 thesis. 380 



The action of choline acetylase was found to be strongly inhibited by 

 methylnaphthoquinone, which has a strong vitamin K action, and also by 

 2-methyl-l,4-naphthoquinone-8-sulfonic acid. 370 Beiler et a 7 .. 381 reported 

 that vitamin P and certain other compounds with a flavonoid structure 

 inhibit the choline acetylase action in vitro. It is suggested in this case that 

 the inhibition may be due to the quinone-forming properties of these com- 

 pounds. 



e. Chlorophyllase. Although chlorophyllase is not present in the secre- 

 tions of the gastrointestinal tract, this enzyme is very widely distributed 

 in the plant kingdom, being present in all green-leaved plants. When 

 consumed in uncooked, green, leafy foods, it may reach the stomach and 

 intestine in an active form. Inasmuch as the optimum pR for its activity 

 is between 6 and 7, the conditions of acidity in the small intestine may be 

 favorable for its action at some periods. 



The enzyme, chlorophyllase, is a relatively specific esterase which hydro- 

 lyzes the phytol ester linkage in chlorophyll-a to yield phytol and chloro- 

 phyllide-a. According to Weast and MacKinney, 382 the reaction varies 

 somewhat with the solvent used, according to (2). 

 Chlorophyll-a(C«H ro N«MgO(COOCH,)(COOC I0 H M )) 



Chlorophyllase 



C 2 h 6 oh at 25°c (Ethyl chlorophvllide-a (C S2 H«,N4MgO(COOCH,)(COOC 2 H,)) 



H 



[Phytol (C 20 H 39 OH) 



(CH,) 2 co at 25°C (Chlorophyllide-a (C«H 3 oN 4 MgO(COOCH,)(COOH)) 



* + 



[Phytol (C 20 H 39 OH) 



1,0 at 75°C. (Chlorophyllide-a (C 32 H 3 oN 4 MgO(COOCH 3 )(COOH)) 



>\ + 



[Phytol (C 2 oH 39 OH) 



The Reactions of Chlorophyll-a (2) 



380 C. Torda and H. G. Wolff, Am. J. Physiol., 169, 150-158 (1952). 



381 J. M. Beiler, R. Brendel, M. Graff, and G. J. Martin, Arch. Biochem., 26, 72-76 

 (1950). 



382 C. A. Weast and G. MacKinney, /. Biol. Chem., 133, 551-558 (1940). 



