Purification and characterization of polygalacturonase from ripened fruits of Musa acuminata cultivar from Kerala (Musa acuminata cv. Palayankodan)

摘要

Bananas are the fruit crop with strong economic and nutritional relevance. This fruits have a very short shelf life due to the softening of the pulp during ripening. Fruit softening is an important aspect of ripening process in fleshy fruits and is caused by the cumulative action of a group of cell wall modifying enzymes. The present study reports characterization of polygalacturonase (PG) isoforms from ripened fruits of Musa acuminata cv. Palayankodan. Three isoforms of PG was purified by ammonium sulphate fractionation followed by DEAE cellulose ion exchange chromatography and gel filtration using Sephadex G 100. Three isoforms showed two subunits on SDS-PAGE and a single band on native PAGE. Enzyme showed maximum activity at pH 4 (PG1, PG2) and 3.5 (PG3). Fe3+ activated PG1 and PG2, while Ca2+ reduced the activity of all isoforms. Km value for substrate polygalacturonic acid was 0.013, 0.015 and 0.011 % for PG1, PG2 and PG3 respectively.