Relationships between nutritional quality of dietary proteins and hepatic polyribosome profiles in rats

Rats were adapted to a feeding period of 5 hours per day and meal-fed a diet containing 10% casein, wheat-gluten, corn-gluten, soya protein, gelatin or whole egg protein as a source of protein. The aggregation of hepatic polyribosomes was highest with whole egg protein as the protein source, followed by casein, soya protein, corn-gluten, wheat-gluten and gelatin in that order. The supplementation of each limiting amino acid to each dietary protein caused more aggregation of hepatic polyribosomes as compared with each non-supplemented diet. These differences of the aggregation of hepatic polyribosomes were closely correlated with their proportion of fullness of the limiting amino acid toward the requirement for maximum growth in young rats and with the biological value for these proteins. These results suggest that the polyribosome profile might directly reflect the hepatic protein synthesis in vivo and could be used as an index of nutritional evaluation of dietary proteins.