| Abstract | Thatcher wheat plants were labelled with ¹⁴C by injecting radioactive tracers into the top internode of the stem during late stages of plant growth. The distribution of ¹⁴C in fully mature plants was examined, emphasis being placed on the labelling of kernel-protein amino acids.Glutamine was only slightly more effective than glutamic acid for labelling glutamic acid isolated from the gluten hydrolysate, indicating that glutamic acid and glutamine are extensively interconverted in the wheat plants. Proline and glutamic acid also are readily interconverted, proline-¹⁴C yielding protein in which the glutamic acid has a higher specific activity than does the proline. By contrast, arginine-5-¹⁴C did not yield highly labelled glutamic acid.¹⁴C from glyoxylate-1-¹⁴C was widely distributed among kernel components but it produced glycine and serine with carboxyl carbons of exceptionally high specific activity.Succinate-1,4-¹⁴C, succinate-2,3-¹⁴C, and aspartic acid-¹⁴C all labelled glutamic acid of kernel protein more extensively than the other amino acids of the protein. The role of the tricarboxylic acid cycle in utilizing these tracers is discussed. |
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