Peptide Biosynthesis and Changes in free Amino Acid Composition in Developing Bean Seedlings (Phaseolus vulgaris)

Abstract

Bean seedling homogenates incorporated labelled [14_C] aspartate, [14_C] glutamate and [14_C] glycine into a number of hydrolyzable radiopositive compounds, as detected by an X-film technique from the thin-layer chromatography plates. The original labelled amino acids in these compounds could be identified by re-chromatography of their acid hydrolysates. The structures of these compounds are still under study, but they seem to be short-chain tri- pentapeptides, synthesized apparently directly from amino acids by the cyto-plasmic peptide synthetases. Both dry and swollen beans contained considerable concentrations of free amino acids, the amounts of which mostly decreased as the seedlings grew, although the concentrations of glutamine and γ-aminobutyric acid increased.