LIPID STORAGE UNDER ABNORMAL CONDITIONS 643 



preventing the accumulation of fat in the liver. On the other hand, Chan- 

 non and Wilkinson 603 were the first workers to attach significance to this 

 finding; they investigated the effect of casein, when included in the diet in 

 amounts varying from 5 to 50%, on the fatty infiltration in the liver. 

 Fatty livers developed in the two groups receiving the lowest casein intake, 

 namely 5%. These authors suggested that certain amino acids might be 

 transformed by the rat into choline. This hypothesis was not an improb- 

 able one ; Rosenf eld 604 had suggested that glycine might be the mother sub- 

 stance of choline, while Engeland 605 had proposed that betaine might origi- 

 nate in the tissues by a methylation of some of the amino acids. The 

 hypothesis that a protein constituent controls liver fat was further sup- 

 ported by Best and Channon. 563 



In an extension of the work on casein, Beeston, Channon, and Wilkinson 606 

 found that, whereas increased amounts of casein in the diet caused a de- 

 crease in neutral fat in the liver, higher levels of phospholipid and chole- 

 sterol oleate obtained. On the other hand, when the casein intake was at 

 50%, the level of cholesterol esters in the liver was reduced. As a result of 

 these experiments, it seemed probable that the effect of protein in prevent- 

 ing fatty infiltration of the liver might differ from that of choline. The 

 maximum effect of casein was exerted when it was present at a 30% level in 

 a diet containing 40% fat. One gram of casein was calculated to have the 

 same lipotropic action as 7 to 8 mg. of choline. 607 ' 608 



However, all proteins are not active in preventing fatty livers. Thus, 

 arachin, a protein from the peanut, was found by Singal and Eckstein 609 

 to lack a lipotropic action. Gelatin was likewise reported by Best et al. 601 

 to have no significant activity, although Channon and associates 610 later 

 reported that gelatin had a slight but demonstrable action on liver fats. 

 The lipotropic activity of a number of proteins was shown by Channon et 

 al. 610 to be in the following descending order: gromax and whale muscle 

 protein, casein (caseinogen), albumin, beef muscle protein and edestin, 

 fibrin and gliadin, and gelatin and zein. In general, according to Tucker 



603 H. J. Channon and H. Wilkinson, Biochem. J., 29, 350-356 (1935). 



604 G. Rosenfeld, Biochem. Z., 218, 48-53 (1930). 



605 R. Engeland, Ber., 42, 2962-2969 (1909). 



606 A. W. Beeston, H. J. Channon, and H. Wilkinson, Biochem. J., 29, 2659-2667 

 (1935). 



607 C. H. Best, R. Grant, and J. H. Ridout, J. Physiol, 86, 337-342 (1936). 



60s a.. W. Beeston, H. J. Channon, J. V. Loach, and H. Wilkinson, Biochem. J., SO, 

 1040-1046 (1936). 



609 S. A. Singal and H. C. Eckstein, Proc. Soc. Exptl. Biol. Med., 41, 512-513 (1939). 



610 IT. J. Channon, J. V. Loach, P. A. Loizides, M. C. Manifold, and G. Soliman, Bio- 

 chm, •/•, 32, 976-985 (1938). 



