TURNOVER OF SHORT-LIVED PROTEINS IN CHICK LEUKOCYTES FOLLOWING DIETARY TREATMENTS

The effect of protein intake (10 vs. 20%) on synthesis and degradation of short-lived leukocyte proteins in vitro was shown in 21-day-old ch icks. Protein synthesis was measured for 1 or 2 h and protein degradat ion for 1.5 or 4 h following an 8-day dietary treatment. Leukocyte pro teins were fractionated on a slab gel into Ii or 100 fractions, and th e imaging radioactivity was calculated for protein synthesis and degra dation. The degradation rates in most of the protein fractions were hi gher in the leukocytes of chicks fed 20% dietary protein than in those fed 10% protein. Protein fractions of M-r similar to 25-37 kD exhibit ed the most marked differences between the two dietary treatments. Thi s technique of measuring turnover rates of short-lived proteins in leu kocytes could potentially be used to examine the effect of nutritional treatments in animals and man as well as to check the effect of catab olic conditions in humans on protein turnover.