Separation and characterization of endopolygalacturonase and exopolygalacturonase from peaches.
Two polygalacturonases (PG I and PG II) have been separated from extracts of ripe peaches (Prunus persica) by chromatography on Sephadex G-100. PG I hydrolyzes polygalacturonic acid from the nonreducing ends of the molecules, releasing galacturonic acid as the product. It functions optimally at pH 5.5, requires Ca(2+) for activity, and hydrolyzes low molecular weight substrates most rapidly. In contrast, PG II cleaves the molecular chain of the substrate randomly with a pH optimum at about 4. This enzyme is most reactive with substrates of intermediate molecular weight. It catalyzes the release of water-soluble, but 70% ethanol-insoluble, pectin from washed peach cell walls.
Pressey
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Richard B. Russell Agricultural Research Center, United States Department of Agriculture, Agricultural Research Service, P. O. Box 5677, Athens, Georgia 30604.
Avants
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