Kinetic study of mixed alpha glucosidase activity induced in honeybee hemolymph by in vivo injection of trehalose
Morgan, M.R.; Bounias, M.
Comptes Rendus des Seances de la Societe de Biologie et de ses Filiales 185(5): 345-356
1991
ISSN/ISBN: 0037-9026 PMID: 1806194 Document Number: 381871
In vivo injection, into emerging bees, of a quantity of trehalose sufficient to double the initial natural haemolymph level of the sugar, leads first to a reduction in the maximal velocity (Vm) of the alpha-glucosidase activity, after 2 hours, followed by an increase in Vm at 6 hours, then a return to normal. The substrate constant (KR) shows minor and insignificant fluctuations about the initial value, and the Hill coefficient (h) a slight, but significant, rise 2 h and 8 h after injection. The simultaneous injection of a protein synthesis inhibitor (ISP) reduces the changes in Vm and h, and lowers value of the ratio Vm/KR from 6 h to 16 h after injection. The overall pattern of results prompts the hypothesis of an intermediary ISP-sensitive induction of an inhibitor of the enzyme-substrate complex, preceding the phase of induction or liberation of active enzyme molecules whose aggregation is subject to a succession of rearrangements alternately favourable to sucrose (lesser specificity) or to trehalose (heightened specificity).