Factors that cause the β-anomeric preference of Na+/glucose cotransporter for intestinal transport of monosaccharide conjugates

The intestinal transport of glucose- and galactose-conjugated acetaminophen (APAP glycoside) by Na+/glucose cotransporter (SGLT1) was studied. SGLT1-mediated transport of APAP glycosides preferred glucoside> galactoside and beta-anomer > alpha-anomer. These preferences agree with previous studies, NMR spectroscopic and molecular modeling studies indicated that the conformation of the glucose ring of alpha- and beta-glucosides of APAP, as well as glycosides in previous studies, is in the C-4(1) chair form, the same form as glucose itself, Molecular dynamics analysis also indicated that the glucose ring was in the C-4(1) chair form, and that there are differences between the rotational spaces of aglycones and hydroxy groups of glucose moieties between anomers. Therefore, we conclude that the beta-anomeric preference of glucose conjugate transport by SGLT1 is not due to the conformation of the glucose ring, but to the configuration of the aglycone at C-l of the monosaccharide moiety. (C) 1998 Elsevier Science B.V. All rights reserved.