674 VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



boxypeptidase, papain, 803 ' 804 and ficin 804 may possibly serve in a similar ca- 

 pacity. 



Proof that the anti-fatty-liver fraction in the pancreas is an enzyme has 

 likewise been adduced from the behavior of preparations from the pancre- 

 atic gland. Thus, Entenman et al. m were able to prepare an anti-fatty-liver 

 fraction from pancreas which maintained normal livers in depancreatized 

 dogs for as long as six months when the material was given in doses of 60 

 mg. daily. This substance was prepared by a procedure differing from 

 that of lipocaic. Moreover, it was shown that lipocaic as prepared by 

 Dragstedt et al. 78,7 was a relatively poor source of lipotropic material. 806 The 

 active lipotropic fraction prepared from pancreas did not owe its activity to 

 its choline content. 807 It caused an increase in plasma choline either by in- 

 ducing a shift of this substance from the tissues to the plasma or, more prob- 

 ably, by stimulating the synthesis from its precursors. 808 However, En- 

 tenman et aZ. 798 did report that the appearance of fatty livers in dogs de- 

 prived of the external excretion of the pancreas by ligation of the duct could 

 be completely prevented by the daily ingestion of 2 g. of choline chloride. 



Methionine was later shown by Chaikoff et al. m to prevent fatty livers in 

 insulin-treated, depancreatized dogs. The conclusion was therefore drawn 

 that the action of the anti-fatty factor in the pancreas is not concerned with 

 the synthesis of choline in the body, or with its action upon the liver as a 

 lipotropic agent, but rather with the liberation of bound methionine con- 

 tained in dietary protein. Chaikoff et aZ. 809 postulate that the anti-fatty- 

 liver factor might be a proteolytic enzyme without which ingested proteins 

 cannot exert their lipotropic action. This viewpoint is supported by sub- 

 sequent evidence supplied by these workers, 810 to the effect that, whereas 

 unhydrolyzed casein failed to maintain a normal level of liver lipids in in- 

 sulin-treated, depancreatized dogs, hydrolyzed casein was effective. Since 

 the methionine content of the latter preparation was sufficient to account 

 for this action, it is suggested that the anti-fatty -liver factor of pancreas 



804 H. Feinberg, I. L. Chaikoff, and C. Entenman, Proc. Soc. Exptl. Biol. Med., 80, 

 161-162 (1952). 



805 C. Entenman, I. L. Chaikoff, and M. L. Montgomery, /. Biol. Chem., 155, 573-578 

 (1944). 



806 C. Entenman, M. L. Montgomery, and I. L. Chaikoff, Am. J. Physiol, 141, 221-226 

 (1944). 



807 C. Entenman and I. L. Chaikoff, /. Biol. Chem., 188, 477-485 (1941). 



808 1. L. Chaikoff, C. Entenman, and M. L. Montgomery, /. Biol. Chem., 160, 387-395 

 (1945). 



809 I. L. Chaikoff, C. Entenman, and M. L. Montgomery, J. Biol. Chem., 160, 489-492 

 (1945). 



810 1. L. Chaikoff, C. Entenman, and M. L. Montgomery, J". Biol. Chem., 168, 177-181 

 (1947). 



