Comparative Threonine,Valine,Histidine,and Glucose Oxidation in Chicks. ∗

Summary

When different amounts of uniformly labeled L-threonine, L-valine, L-histidine, or glucose were administered intraperitoneally to young chicks previously fed complete purified diets or diets lacking different essential amino acids, the total percentage of administered activity recovered as C¹⁴O₂ during 14 hour experimental periods averaged 10% for threonine, 25% for histidine, 40% for valine, and 50% for glucose. There were large differences in the fraction of each amino acid incorporated into picric acid-precipitable protein. Peak C¹⁴O₂ production occurred about one hour after administration of glucose, threonine, or valine; 2 hours after administration of histidine. Neither previous diet (complete or lacking the amino acid injected) nor 10-fold variations in amounts of amino acids administered appeared to affect fractions oxidized or synthesized into proteins.