Erwinia carotovora(Jones)Hollandの生産する2種の液化型ペクチナーゼについて : II. Endo-polymethylgalacturonaseとendo-polygalacturonaseの性質の比較

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Four isolates of Erwinia carotovora, which are characterized by their high productivities of DPb, were used for the comparative studies of two depolymerases, DPa and DPb. 1. The pH relationship to the activity of two DPa differed according to the isolates (see Table 1, 2 and Fig. 1). In general, DPa was active in a pH range from 5.0 to 9.0 or above while DPb was active in a pH range from 3.5 to 6.O; their optimum pH lie at 7.0〜9.0 and 4.0〜4.5 respectively. DPa of the isolate Chr. 10 was characteristic in respect that the activity, at pH 8, was very much increased through dialysis. Since two depolymerases were quite different in their optimum pH they were easily distinguishable by measuring viscosity decreases of the substrate at the optimum pH 7.0〜9.0 and 4.0〜4.5, respectively. With all the isolates tested, both DPs were rapidly inactivated when kept at pH 2.7. At a high pH, 10.5, the effect of pH on DPa activity differed according to the isolates, DPa of the isolate C1 being rapidly inactivated, whereas that of the isolate CVII very much stimulated. DPb was very stable against the alkaline treatment irrespective of the isolates. 2. The optimum temperature ranges for the activity of DPa lie between 20° and 40°, while those of DPb between 30°and 50°C. At lower temperatures there was a great difference in the activities of both DPs between isolates C1 and 551. Both enzymes of most isolates were inactivated by hot water treatment at 60℃ for ten minutes, except for DPa of the isolate C1 which maintained about 65 per cent of activity after this treatment. 3. DPb, after losing its activity by the dialysis in tap water, was reactivated by the addition of cations such as K^+, Na^+, Mg^<++> and NH_4^+, the extent of recovery varying according to the cations and also to the isolates, but was not by Ca^<++> except for DPb of isolate CVII which was very effectively reactivated by Ca^<++>. DPa activity was very much stimulated by Ca^<++>, but inactivated by Mg^<++> to varying degrees according to the isolates. 4. The DPa activity at alkaline side was directly proportional to the methoxyl content of the substrates, suggesting that this enzyme decomposes more easily the high methoxyl pectin than pectic acid or low methoxyl pectinic acid. Reversely, DPb decomposed more easily pectic acid or pectinic acid than pectin. No trace of reducing group was detected in the course of reaction within an hour. From these results, it is concluded that DPa of E. carotovora is identical with endo-polymethylgalacturonase after Demain and Phaff(1957), to which Wood's depolymerase has been attributed, and DPb is identical with endo-polygalacturonase. The possible courses of pectin break down by E. carotovora were discussed.
日本植物病理学会の論文
1963-01-30

Erwinia carotovora(Jones)Hollandの生産する2種の液化型ペクチナーゼについて : II. Endo-polymethylgalacturonaseとendo-polygalacturonaseの性質の比較

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