Studies on Wheat Plants Using C14compounds: Vii. Utilization of Pyruvate-2-C14

Approximately half of the carbon-14 injected into the stems of wheat plants in the form of pyruvate-2-C14remained in the plant at maturity, 30 days later. Almost 90% of this had accumulated in the kernel. Appreciable activity was found in the major components, protein, starch, ether-soluble material, and a residue termed bran. The amino acids of the gluten protein differed markedly from one another in specific activity. Glutamic acid and the related amino acids, arginine and proline, were most active, their specific activity decreasing in that order. Fifty-two per cent of the carbon-14 in glutamic acid was in carbon-5, while carbon-1 contained 21%. Seventy per cent of the radioactivity of aspartic acid was divided almost equally between the terminal carboxyl groups. The results are similar to those previously observed using acetate-1-C14as tracer, and it is concluded that administered pyruvate-2-C14undergoes extensive decarboxylation to form acetate-1-C14. The most active carbon in alanine from the pyruvate-2-C14was carbon-1. This observation is not in accord with the theory that alanine is formed directly from pyruvate by transamination.