Purification and characterization of a rhamnogalacturonase with protopectinase activity from Trametes sanguinea

In a culture filtrate of Trametes sanguinea IFO 6490, we found a protopectin-solubilizing enzyme, protopectinase-T, that did not degrade polygalacturonic acid. The enzyme was purified to homogeneity with hydrophobic, cation-exchange, anion-exchange, and size-exclusion chromatographies. It had an apparent molecular mass of 55 kDa by SDS/PAGE and 39 kDa by size-exclusion chromatography on Superose 12. The isoelectric point was at pH 8.1. Protopectinase-T was stable from pH 3.0 to 6.0 and at temperatures up to 50 degrees C. The optimum pH for enzyme activity was 4.0 at 37 degrees C, and the optimum temperature was 50 degrees C at pH 5.0. Protopectinase-T catalyzed the release of highly polymerized pectin from lemon peel protopectin.