8 BULLETIN 717, U. S. DEPARTMENT OF AGRICULTURE. 



same amount of lysine as gliadin. However, the amomit of these cereal 

 proteins in some of the cereals is insufficient to supplj- adequate 

 amounts of the essential amino acids, whereas soy beans and peanuts 

 are rich in glycinin and arachin which yield a high percentage of 

 lysine. In considering the dietary value of glycinin and arachin, 

 from the standpoint of lysine and tryptophane, the consensus of 

 opinion of biochemists seems to be well summed up in the conclusions 

 of Osborne and Mendel ^ who state " We have shown that growth does 

 not occur when lysine is lacking from the diet but takes place 

 promptly on adding this amino acid to the otherwise adequate food," 

 and in the conclusions expressed by Abderhalden,^ who says that 

 tryptophane is an indispensable component in the dietary. 



It may also be noted, in discussing the relative nutritive value of 

 proteins as regards the presence or absence of lysine and tryptophane, 

 that Osborne and MendeP state that lysine must be present in the 

 diet since "the animal organism apparently can not synthesize 

 lysine." These authors ^ also state that ''Tryptophane can not be 

 synthesized by the animal cells." Accordingly, a theoretical con- 

 sideration of the relative nutritive value of soy-bean and peanut pro- 

 teins, based upon their amino-acid content alone would indicate that 

 glycinin and arachin possessed a greater dietary value than the prin- 

 cipal proteins supplied by the common cereals. 



BIOLOGIC VALUE OF SOY-BEAN AND PEANUT PROTEINS AS COMPARED 

 WITH THAT OF COMMON CEREAL PROTEINS. 



Feeding experiments have been made by a number of investigators 

 for the purpose of securing data regarding the relative biological 

 value of proteins supplied by some of the cereals referred to above. 

 Willcock and Hopkins ^ state that ''loss of weight begins the moment 

 it [zein] forms the sole nitrogenous supply." Osborne and Mendel® 

 report "We have now accumulated the results of a large experience 

 in feeding zein, with the uniform consequence of decline when this 

 protein forms the sole nitrogenous component of the dietary." These 

 results have been confirmed by Wheeler '^ in studies with rats and 

 later by Hart and McCollum,^ who report that young pigs can not 

 grow when the maize kernel is the sole source of nutriment. Hogan ^ 

 conducted experiments to determine the value of corn protein, zein, 

 when fed as the sole source of protein, and concluded that trypto- 



1 Jour. Biol. Chcm., 25 (1916), No. 1, p. 2, figs. 4. 



2 Hoppc-Seyler's Ztschr. Physiol. Chom., 96 (1915), No. 1-2, pp. 1-147. 

 > Jour. Biol. Chem., 17 (1914), No. 3, p. 334. 



< Ibid., p. 328. 



» Jour. Physiol., 35 (1906), No. 1-2, p. 1(X). 



« Jour. Biol. Chom., 17 (1914), No. 3, p. 338. 



' Jour. Expt. Zool., 15 (1913), No. 2, pp. 209-223. 



8 Jour. Biol. Chom., 19 (1914), No. 3, pp. 373-395, pis. 2, flgs. 11. 



» Jour. Biol. Chom., 29 (1917), No. 3, pp. 485-493, figs. 3. 



