Expolygalacturonase from Suspension Cultures of Marchantia polymorpha: Its Presence and Involvement in Pectic Polysaccharide Degradation.

Polygalacturonase was isolated from cell suspension cultures of a thalloid liverwort, Marchantia polymorpha. The enzyme in the ;buffer-soluble' protein fraction was dialyzed at pH 5.2 and further purified 91-fold by a combination of chromatographic techniques including CM-Sephadex, Sephacryl S-200, DEAE-Sephadex, and Sephadex G-200. The purified enzyme had an optimum activity in the pH range at 3.6 to 3.8 and molecular weight of 76,000 daltons, and its activity was not stimulated by cations. The enzyme was identified as an exohydrolase from viscometric data and chromatographic analysis of the reaction products.The polysaccharides extracted from the Marchantia cell walls with 2% (w/v) Na hexametaphosphate solution were separated into two fractions, neutral polysaccharides (fraction P-N) and acidic polysaccharides (fraction P-A) by a DEAE-Sephadex column. The fraction P-N was not susceptible to the purified exopolygalacturonase, whereas fraction P-A was partially degraded. This resulted in hydrolysis of 19.5% of the glycosyl linkages of fraction P-A with the release of galacturonic acids. The specific activity of exopolygalacturonase increased during the growth cycle.