Inhibition of in Vivo Conversion of Methionine to Ethylene by l-Canaline and 2,4-Dinitrophenol

Abstract

L-Canaline, a potent inhibitor of pyridoxal phosphate-mediated reactions, markedly inhibited the conversion of methionine to ethylene and carbon dioxide by apple tissue. A 50% inhibition of methionine conversion into ethylene was obtained with 50 μm canaline and almost complete inhibition with 300 μm canaline. When 2,4-dinitrophenol, an oxidative phosphorylation uncoupler, was fed to apple tissue, it inhibited the conversion of radioactive methionine to ethylene by 50% at a concentration of 60 μm and by 90% at a concentration of 100 μm. Production of labeled carbon dioxide from acetate-1-¹⁴C was increased by 2,4-dinitrophenol, indicating that the inhibition of ethylene production was due to uncoupling of phosphorylation. Auxin-induced ethylene production by mungbean (Phaseolus mungo L.) hypocotyl sections was similarly inhibited by these inhibitors.