Chemical modification of the small intestinal Na+/D-glucose cotransporter by amino group reagents. Evidence for a role of amino group(s) in the binding of the sugar.

Some amino group reagents inactivate the small-intestinal Na+/D-glucose cotransporter, as measured either as a catalyst of Na+-dependent D-glucose transport or as a Na+-dependent phlorizin ligand. The amino group(s) studied in this paper are not identical with those investigated previously (Biber, J., Weber, J. and Semenza, G. (1983) Biochim. Biochim. Acta 728, 429-437): these are protected from inactivation by the simultaneous presence of Na+ plus sugar substrates. They are thus likely to be located within the substrate-binding site.