| Abstrakt: |
Treatment of Rhizobium leguminosarum bv phaseoli bacteroids with 25 m M citrate buffer, pH 4.0, prior to treatment with 50 m M Tris, pH 8.0, containing 1 m M EDTA, 20% (wt/vol) sucrose, and 1 mg lysozyme/mL increased by two- to three-fold the release of the periplasmic marker enzymes phosphodiesterase and pyrophosphatase. Release of malate dehydrogenase, a cytoplasmic marker, was largely unaffected by the citrate pretreatment. The pretreatment was shown to be a pH effect, with a narrow optimum pH range. Above pH 4.0 the enhancement of release of periplasmic enzymes decreased sharply to almost no effect at pH ≥ 5.5, and below pH 4.0 release of malate dehydrogenase increased sharply. The effectiveness of pretreatment with low pH did not appear to be owing to increased entry of lysozyme into the periplasmic space, and an effect of low pH on the suceptibility of the peptidoglycan layer to hydrolysis is suggested. [ABSTRACT FROM AUTHOR] |
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