Erwinia carotovora (Jones) Holland の pectin-methyl-esterase の性質, 特に2, 3 の植物性酵素との比較

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As the authors described elswhere, a high pectin-methyl-esterase (PME) activity was always detected in the plant tissues attacked by Erwinia carotovora. In order to elucidate the orgin of this enzyme found in diseased tissues, characterization of enzymes differing in source should be made, because PME can be found in the culture of E. carotovora as well as in healthy plant tissues. The present paper presents the results of comparative studies between PME isolated from three isolates of E. carotovora and PME isolated from some vegetables. Isilation of the enzyme from plants (potato, onion and carrot) was made by precipitating the enzyme with 70 percent saturated ammonium sulphate, after extraction with 1/2 diluted MacIlvain's buffer (pH 7.0) and filtration through a layer of diatomaceous earth. The enzyme from the bacterial culture, isolate C1, 551, and 547, was obtained by precipitating with ammonium sulphate of the same concentration as in the above case, after centrifugation at 10.00O R. P. M. for 10 min. The activity of all these enzymes was considerably lowered by dialysis with celophane membrane against tap water for 24hrs. The enzyme activity was lost perfectly, except in the one secreted by the isolate 551, by treatment with ion exchange resins, IR-120 and IRA-400. These solutions recovered their activity by the addition of 0.1 M ammonium sulphate, the activity usually exceeding that of the criginal preparation. As regards the recovery of enzyme activity due to salts, mono-valent cations were most effective in the case of bacterial enzymes, while di-valent cations were most effective in the enzymes of plant origin. Bacterial PME showed, in any isolate, the highest activity at a reaction temperature of 50℃. In PME of plant origin, however, the optimum reaction temperature was from 40℃ to 60℃ according to the kind of plant. The optimum pH value was 7.O in all the enzymes, but another small peak was also found at 4.0 in most enzymes, except the one from the isolate 547. In the cases of C1 and onion enzymes, especially, the activity at pH 4.O was almost of the same order as that at pH 7.O. Most of the enzymes were inactivated by heating at 60℃〜70℃ for 10 min.In addition to the above heat labile enzyme, the isolate 547 produced, after 5 days in the culture medium, a very heat-tolerent enzyme which showed some activity even after heating at 100℃ for 10 min.
日本植物病理学会の論文
1962-01-25

Erwinia carotovora (Jones) Holland の pectin-methyl-esterase の性質, 特に2, 3 の植物性酵素との比較

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