An in vitro kinetic study of the mixed inhibition of honeybee hemolymph PNP-α-D-glucosidase by sucrose

Abstract

Sucrose acts in vitro as a mixed inhibitor of (V+K+n) type towards honeybee hemolymph PNP-α-D-glucosidase activity. Between the stages of emergence and foraging, there is little change in the effect of the inhibitor on VM (fi=from 1.31 to 1.35 respectively) or n (fi=from 1.09 to 1.07) but K is more markedly affected (fi−1=from 1.17 to 1.87)M. These observations reflect the decrease of Ki from 277 to 98 mM and of I50 from 154 to 111 mM, but K′i scarcely alters during development (from 477 to 425 mM). These inhibitory effects of sucrose are intermediate between those previously reported for trehalose and glucose.