Molecular activation of a trehalase purified from the fat body of a coleopteran insect (Tenebrio molitor), by an endogenous insulin-like peptide.

Trehalase is the major factor involved in the release of glucose in the various insects organs. During physiological regulatory processes, and particularly during the induction or breaking of diapause, insulin-like factors are involved. Then, by contrast with the classical hypoglycemic role of insulin, the insulin-like peptide isolated from the insect (brain and/or fat body) is also able to activate the fat body trehalase in vitro, through a direct molecular interaction. The mechanism involves the binding of the activator to the "trehalase-trehalose complex", rather than on the free enzyme, without change in the Hill coefficient nor in the maximum velocity (Vmax). The rate constant KR is conversely proportional to the activator concentration. This mechanism can be totally quenched by adding an anti-serum anti-insulin-like factor in the reaction medium.