Quantitative analysis of the kinetics of stilbenedisulfonate binding to band 3

James M. Salhany, Renee L. Sloan, Karen A. Cordes, Lawrence M. Schopfer

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Stilbenedisulfonates are potent inhibitors of erythrocyte band 3 chloride/bicarbonate exchange. Band 3 exists as dimers and tetramers in situ, and each monomer binds one stilbenedisulfonate molecule. We determine: (a) whether stilbenedisulfonates exhibit cooperativity in reversible binding to the Band 3 dimer, and (b) whether stilbenedisulfonates directly compete with chloride. Stopped-flow and static fluorescence spectroscopy were used to measure the kinetics and equilibrium of DBDS (4,4′-dibenzamido-2,2′-stilbenedisulfonate) binding to isolated and membrane-bound Band 3. DBDS binding showed biphasic kinetic time courses which were consistent with a two step mechanism: {A figure is presented} Static binding studies showed no evidence for cooperativity, in agreement with the kinetic measurements. Chloride (150 mM) strongly affected the second step in the binding process by increasing k-2 about 20-fold, without significantly affecting k1, k-1 or k2. Our results indicate: (a) that DBDS binds independently to each monomer of the band 3 dimer, and (b) that DBDS is not competitive with chloride for binding to the transport site, but rather interacts with the transport site allosterically.

Original languageEnglish (US)
Pages (from-to)953-964
Number of pages12
JournalInternational Journal of Biochemistry and Cell Biology
Volume27
Issue number9
DOIs
StatePublished - Sep 1995

Keywords

  • Allosteric site-site interaction in membrane transport
  • Anion exchange proteins
  • Chloride transport
  • Membrane proteins
  • Stopped-flow fluorescence

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology

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