Insect trehalose-6-phosphatase: The unactivated type, as illustrated in Periplaneta americana, and a survey of the ordinal distribution of the two presently known types

Abstract

1. 1. Trehalose-6-phosphatase, one of the two enzymes making up the trehalose synthetase complex in insects, is, in Phormia regina (Diptera: Calliphoridae), also capable of hydrolysing glucose-6-phosphate at a significant rate, the reaction being activated by trehalose. 2. 2. The properties of this enzyme in the American cockroach ( Periplaneta americana) indicate that it is different from the “ Phormia” type. It has a K m T-6-P of 2.09±0.88 mM; pH optimum = 7.0; mol. wt = 108,000 daltons; activity vs glucose-6-phosphate negligible; no activation of glucose-6-phosphate hydrolysis by trehalose. 3. 3. A survey of representatives of a number of insect orders shows that trehalose activation is restricted to certain related families in the order Diptera.