Ethylene Production by Cell-Free Extract of the Kudzu Strain of Pseudomonas syringae pv. Phaseolicola

概要

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A cell-free ethylene-forming system of Pseudomonas syringae pv. phaseolicola (Kudzu strain) was characterized by its psychrophilic trait. Ethylene was most effectively produced from α-ketoglutaric acid (α-KG) at 0.5 mM followed by glutamate and then histidine at 5 to 10 mM. The presence of FeSO_4 was essential to the cell-free system. DTT and histidine greatly stimulated ethylene production; the latter could be substituted to some extent by its analogues. The optimum pH value and temperature for the ethylene-forming reactions were pH 7.0 and 25℃, respectively. Ethylene formation from α-KG was inhibited in the presence of carbonates or organic acids of the TCA cycle, whereas that from glutamate was inhibited in the presence of ammonium salts. Ethylene production from α-keto-γ-methylthiobutyric acid in the cell-free system was largely dependent on non-enzymical processes in the presence of DTT and FeSO_4. The ethylene-forming reactions were inhibited completely by 1 mM n-propyl gallate and 1 mM p-chloromercuribenzoic acid and partly by coenzymes such as pyridoxal-1-phosphate, folic acid, and flavin mononucleotide at 5 mM. The complete system for the highest ethylene production consisted of: 0.5 mM α-KG, 50 mM HEPES (pH 7.0), 5 mM DTT, 0.5 mM FeSO_4, and 10 mM histidine. The amount of ethylene produced in this system was equivalent to 40 to 50% of that produced by the living cells.
日本植物生理学会の論文