Selection of a high-energy bioactive conformation of a sulfonium-ion glycosidase inhibitor by the enzyme glucoamylase G2

M. A. Johnson, M. T. Jensen, Birte Svensson, B. M. Pinto

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Transferred nuclear Overhauser effect and rotating-frame Overhauser enhancement NMR spectroscopies are used to probe the conformation of a bicyclic sulfonium ion, which is an analogue of the naturally occurring glycosidase inhibitor castanospermine, bound to the enzyme glucoamylase G2. Enzyme inhibition assays indicate that the bicyclic sulfonium ion is a slightly better inhibitor (K(i) = 1.32 mM) of glucoamylase G2 than the naturally occurring sulfonium-ion glycosidase inhibitor, salacinol, with a K(i) value of 1.7 mM. The NMR results are interpreted in terms of the selection by the enzyme of a high-energy conformation of the ligand that is already represented in the ensemble of free-ligand conformations.
Original languageEnglish
JournalJournal of the American Chemical Society
Volume125
Pages (from-to)5663-5670
ISSN0002-7863
Publication statusPublished - 2003
Externally publishedYes

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