EFFECT OF PARTIAL DEGLYCOSYLATION ON CATALYTIC CHARACTERISTICS AND STABILITY OF AN AVOCADO PEROXIDASE

An isoperoxidase (EC 1.11.1.7) purified from avocado (Persea americana Mill. cv. Topa Topa) leaves, lost 35% of its glycosidic moiety after incubation with glycopeptidase F (EC 3.2.2.18). The partial removal of carbohydrate chains caused a decrease in the K-m for reductor substra tes (guaiacol, syringaldazine and indole-3-acetic acid) and favoured t he enzyme activation by Ca2+. A decrease in stability against temperat ure was also observed. Our results are consistent with the hypothesis that the carbohydrate moiety located on the surface of the peroxidase molecule acts as a molecular shield.