Crossed hydrophobic interaction immunoelectrophoresis: An analytical method for detection of amphiphilic proteins in crude mixtures and for prediction of the result of hydrophobic interaction chromatography

Crossed hydrophobic interaction immunoelectrophoresis is an analytical technique in which the principles of quantitative immunoelectrophoresis and hydrophobic interaction are directly combined. Using phenyl-Sepharose as hydrophobic (amphiphilic) matrix we have shown how the method permits detection of amphiphilic proteins in three model systems: native- and trypsinated intestinal brush border aminopeptidase, serum proteins, and detergent-solubilized erythrocyte proteins. In the case of first system the relative amounts of the two forms of the enzyme have been determined using immunochemical quantification. Comparison of the present method with column hydrophobic interaction chromatography reveals concordant results for both serum and erythrocyte proteins. Tests of some alkyl-substituted agaroses show that they work in a manner similar to phenyl-Sepharose.