The binding of cationic detergent to insulin, zinc-insulin and iso-insulin

Insulin, zinc-insulin and iso-insulin were precipitated by cetyltrimethylammonium bromide when the detergent/protein molar ratio was less than 10:1, whereas no precipitation was observed at ratios greater than 10:1. It is concluded that the detergent binds as a dimer at each binding site at ratios greater than 10:1. U.v. difference spectra indicated that the tyrosine residues were perturbed by detergent binding.