ANNUAL REPORT. 1940 11 



exposed to dry heat for 96 hours at 125° C. These proteins were tlien 

 incorporated into a 25 percent galactose ration in amounts to furnish 15 

 percent of protein. The ration was entireh^ adequate in other factors. 



The growth value of these proteins was damaged by heat in the de- 

 creasing order: gluten, casein, fibrin, egg albumin. The anti-cataract- 

 ogenic property was reduced by heating in the decreasing order: casein, 

 egg albumin, gluten, fibrin. Thus these two properties of protein were 

 not damaged to the same degree by exposure to dry heat. It follows 

 that, if the protective factor is an amino acid or group of amino acids, 

 they are not necessarily the same as those essential for growth. 



The blood-sugar values tended to be higher in the rats fed heated casein 

 than in the plain casein groups but were not significantly different for 

 the other proteins before and after heating. It would appear that the 

 degree of galactemia cannot alone account for the difference in tlie degree 

 of lenticular injury observed. Thus it seems that the protein factor may 

 be protective in the presence of the high blood galactose. 



3. The Effect of the Hydrolytic Products of Casein and Deaminizcd Casein 

 on the Cataractogenic Action of Galactose. (E. L. Moore. M. D. Henderson 

 and H. S. Mitchell. J. Nutri. 21, Feb. 1941.) (Department of Chemistry 

 cooperating.) Preliminary work showed that deaminized casein was more 

 protective against galactose cataract in rats than ordinary commercial 

 casein from which it was prepared. Other work has indicated that the 

 type of treatment which alters the growth value of a protein may or may 

 not affect its anti-cataractogenic quality. Hydrolytic products of casein 

 and deaminized casein were prepared by both acid and enzymic hydrolysis 

 and were fractionated by Dakin's method. The whole proteins or the 

 h3^drolysates were fed on the basis of the nitrogen equivalent of 10 percent 

 of protein fed as casein. The fractions were fed in amounts proportional 

 to the respective yield of each. 



The enzymic hydrolysate of deaminized casein was somewhat more 

 protective than the deaminized casein from which it was prepared. Of 

 the fractions, the diamino-dicarboxylic acid fraction of the enzymic 

 hydrolysate afforded as much protection as the whole hydrolysate, while 

 tlie monoamino and proline and peptide fractions showed no protection 

 whatever. Blood-sugar determinations indicated that the protective action 

 was exerted in the presence of the high blood sugar and not by a lowering 

 of the blood sugar level. 



4. The Influence of Certain Diainino and Dicavboxylic Amino Acids upon 

 the Catwactogenic Action of Galactose. ( H. S. Mitchell and G. M. Cook.) 

 Following the lead suggested by the work just reported, some individual 

 amino acids are being investigated. Glutamic acid, histidine, and arginine 

 are all present in the protein hydrolysate fraction found to be most pro- 

 tective in the previous work. The amino acids are being fed incorporated 

 in a low-protein galactose ration in order to observe any possible protec- 

 tive action. Results are not yet available. 



5. Time Factors in the Development of Galactose Cataract. (G. M. Cook 

 and H. S. Mitchell.) It has been observed in this and other laboratories 

 that young rats are inore susceptible to galactose injury than older rats. 

 An experiment designed to investigate the question of this age factor is 

 in progress. Rats from the same litter are started on experimental rations 

 at fortnightly intervals. The ones started later require a longer time for 

 lenticular injuries to become evident. The data are not yet complete. 



