Studies on the Amino Acid Metabolism of Higher Plants

Citation

Rogers, Bruce Joseph (1955) Studies on the Amino Acid Metabolism of Higher Plants. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/NB9G-Q853. https://resolver.caltech.edu/CaltechETD:etd-01202004-155710

Abstract

It has been known for some time that the protein level of detached leaves decreases as a result of the excision. The possibility that detached leaves are unable to form certain amino acids has been advanced as a cause for the decrease in the protein level. This hypothesis was tested in the present work. The incorporation with time of carbon-14 from C14-carboxyl-labeled acetate and C14-uniformly-labeled sucrose into the free and protein-bound amino acids of excised organs of red kidney bean (Phaseolus vulgaris) was studied. Of sixteen amino acids investigated, all were found to have incorporated carbon atoms from both acetate and sucrose in the excised leaves, stems and roots. On the basis of this work, it is felt that the decrease in protein level in detached leaves is not due to an inability of leaves to synthesize amino acids. The incorporation of radioactive amino acids (produced in vivo) into leaf, stem and root protein of red kidney bean was studied. It was found that radioactive amino acids are incorporated into root protein much more rapidly than into leaf or stem protein. The enzymatic decarboxylation and oxidation of a number of amino acids was studied in a water extract prepared from acorn squash. Great variation in the relative rates of reaction for the amino acids was demonstrated for both the decarboxylative and oxidative reactions. The partial N-terminal amino acid sequence of pancreatic trypsin inhibitor was found to be arginyl-phenylalanine. It is suggested that the system used would be applicable for the determination of the sequence of small peptides such as those discovered in the work with red kidney bean.

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