FIR BARK (ABIES ALBA MILL.) LECTIN IS AN INHIBITOROF FIR PEROXIDASE 'IN VITRO'

摘要

Abies (Abies alba Mill) bark agglutinin, AbA2 inhibited the peroxidase from the same tissue up to 35% with an IC_(50) of 0.763 x 10~(-2)M. The Km of free Fir peroxidase was 0.249 x 10~(-2)M., while by interaction with 2.1μg/ml of AbA2 the binding efficiency increases 2 times. The kinetic data of the enzymatic activity of Fir bark peroxidase incubated with the AbA2 lectin (0.6-2.1μg/ml) showed a mixed type of inhibition (competitive/uncompetitive). At relatively high concentration of AbA2 lectin (2.1 μg/ml) the mixed inhibition type of Fir peroxidase changed to fairly competitive. Hydrolysis of AbA2 lectin and Fir peroxidase with 5% H_2SO_4, and subsequent dyeing for Fe ions on TLC silicagel plates revealed the existence of Fe~(3+) in the structure of both AbA2 lectin and Fir peroxidase. Incubation of AbA2 lectin with EDTA, as possible chelator of Fe~(3+) increases the peroxidase inhibition changing the behavior into highly competitive. No modifications in peroxidase activity were shown after incubation of AbA2 lectin (1.2μg/m1) with 40 mM of GIN, Ga1N, G1NAc, Ga1NAc and Fuc The interaction of AbA2 lectin with Fir peroxidase at the protein level through Fe~(3+) was discussed.