Electrophoretic studies of clioquinol binding to human serum proteins

Abstract

The binding of radioisotope-labeled clioquinol to human serum proteins in vitro was studied by means of agarose gel electrophoresis. The technique gave a satisfactory separation of free and bound forms of clioquinol without a significant interaction between clioquinol and the supporting medium even at considerably high concentrations of the drug. The clioquinol binding proteins in serum were identified as albumin and lipo-proteins. Clioquinol was bound to albumin at an equimolar ratio with an apparent binding constant of 5.6 × 10 4 M −1. When the amount of clioquinol exceeded the binding capacity of albumin, lipoprotein classes of very low density, low density and high density were capable of serving as auxiliary carrier proteins of clioquinol.