STUDIES ON WHEAT PLANTS USING CARBON-14 COMPOUNDS: XV. UTILIZATION OF SERINE-1-C14AND SERINE-3-C14

Abstract

Thirty-five per cent and 43% of the carbon-14 from DL-serine-1-C14and L-serine-3-C14, respectively, were found in the mature kernels of wheat plants to which the above tracers were administered by injection into the stem during late stages of growth. Total recoveries of carbon-14 in upper portions of the plant were 40% and 35% respectively. Radioactivity was extensively distributed among major kernel components with protein fractions having a somewhat greater specific activity than starch and ether-soluble material. Carbon-14 from both tracers was incorporated into all of the protein amino acids isolated, notable features being an extensive labelling of carboxyl carbon of glycine when DL-serine-1-C14was used and preferential incorporation of serine carbon-3 into histidine. The results are in accord with the view that conversion of serine to glycine occurs largely by loss of serine carbon-3 and that little or no glycine is formed from serine via decarboxylation.