Mechanistic basis for site-site interactions in inhibitor and substrate binding to band 3 (AE1): evidence distinguishing allosteric from electrostatic effects.

Kinetic studies suggest that stilbenedisulfonates inhibit erythrocyte anion exchange by competing with substrate anions for binding to band 3 (AE1). Such competition seems to involve site-site interactions between distinct inhibitor and substrate binding sites. The molecular basis for site-site interactions could be allosteric or electrostatic. In this paper, inhibitor binding kinetic studies are reviewed, and 35Cl(-) NMR line-broadening experiments are presented, both of which seem to rule out an electrostatic hypothesis. The results are consistent with an allosteric site-site interaction mechanism in the binding of stilbenedisulfonate and substrate anions to band 3. (c)2001 Elsevier Science.