Purification and characterization of extracellular, acidic chitinase isoenzymes from elicitor-stimulated parsley cells

Treatment of cultured parsley cells (Petroselinum crispum) with fungal elicitor caused large increases in the activities of chitinase and 1,3-beta-glucanase. Chitinase activity accumulated predominantly in the culture medium, whereas 1,3-beta-glucanase activity was located almost exclusively intracellularly. Extracellular chitinase activity was resolved into six different isoenzymes, all of which were purified and characterized. All six isoforms were acidic proteins (pI 3.8-5.3), with molecular mass 30-38 kDa. Four were exochitinases and two were endochitinases. The most abundant isoform also showed lysozyme activity. Three of the exochitinases were glycoproteins and two of these were reactive with an antiserum specific for xylose in complex glycosidic structures. The exochitinases constituted relatively small proportions of the total chitinase activity and may serve a different function in cellular metabolism compared to the more abundant endochitinases.