d-amino-acid-stimulated ethylene production: Molecular requirements for the stimulation and a possible receptor site

Various kinds of d-amino acids enhanced ethylene production in the cotyledonary segments of Xanthium pennsylvanicum seeds. To be effective they required not only their d-configuration but also the presence of α-NH₂, α-COOH and a hydrophobic as well as a bulky side chain. Moreover, they exhibited almost the same dissociation constant in kinetic analysis. On the other hand, l-phenylalanine and d-serine, which themselves were ineffective in the stimulation of ethylene production, competitively inhibited d-phenylalanine-stimulated ethylene production. Thus, the d-amino-acid-stimulated ethylene production was explained by assuming the existence in cells of d-amino-acid receptor site associated with ethylene synthesis.