A. Quaroni, E. Gershon, G. Semenza
Oct 25, 1974
Citations
0
Influential Citations
48
Citations
Journal
The Journal of biological chemistry
Abstract
Abstract Conduritol-B-epoxide, a compound structurally related to the substrates of sucrase and isomaltase is an active-site-directed inhibitor. The inactivation of sucrase and isomaltase can be complete, is irreversible, and is prevented by the presence of reversible competitive inhibitors and substrates. During the inactivation 1 mole of inhibitor is bound covalently per mole of subunit. The release of the label by treatment with hydroxylamine and the apparent pKa values of the reactive groups suggest that a carboxylate is present in the active sites of both subunits. Fractionation of the tryptic digest of the sucrase-isomaltase complex labeled with [3H]conduritol-B-epoxide shows that the label is bound to a glycopeptide, thus locating the active sites of sucrase and isomaltase near a hydrophilic region.