Molecular Pharmacology, Vol 14, 884-889, Copyright © 1978 by the American Society for Pharmacology and Experimental Therapeutics

Experimental Observation of Ionic Forces in Drug-Protein Interactions as Illustrated by the Binding of Sulfaethidole by Human Serum Albumin

¹ Department of Pharmaceutical Chemistry, Faculty of Pharmacy, State University Utrecht, Catharijnesingel 60, 3511 GH Utrecht, Netherlands

When ionic forces contribute to the binding of drugs by a protein the groups involved in this electrostatic bonding may undergo pK shifts. A pH titration method is described to detect such pK changes. The procedure is illustrated by the binding of sulfaethidole to human serum albumin. For this case changes in pK of groups both of the protein and of the bound drug are observed using this method.

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ACKNOWLEDGMENTS We thank the technical service (head Mr. A. Dirksen) for constructing the titration equipment.