A circular dichroism study of the interaction of chlorpromazine with mouse brain tubulin.

A circular dichroism study with subsidiary ultracentrifuge measurements on the interaction of chlorpromazine with mouse brain tubulin establishes the previous inference from binding studies that the drug induces a change in the structure of the protein. Binding of the first mole of chlorpromazine causes an alteration in secondary structure, which is reversible with respect to drug concentration, without detected change in tertiary structure or significant change in the state of association of the protein. The conformationally altered tubulin binds additional chlorpromazine molecules without further change in secondary structure.