STRUCTURAL ORGANIZATIONS OF HEMOGLOBIN AND MYOGLOBIN INFLUENCE THEIR BINDING BEHAVIOR WITH PHENOTHIAZINES

Binding modalities of chlorpromazine and trifluoperazine, two widely u sed antipsychotic phenothiazine drugs with hemoglobin and myoglobin ha ve been studied to understand how the quaternary, tertiary and seconda ry structural organisations of the proteins regulate the binding proce ss. NaCl-induced alteration in the quaternary structure of hemoglobin influences its binding modality with phenothiazines. Minor alterations in the tertiary structure of thermally denatured myoglobin (denaturat ion temperature ranging between 30-70 degrees C) do not affect its aff inity and the modality of binding with the drugs, but alterations in t he secondary structure of the protein denatured at temperatures betwee n 70-80 degrees C ifluence its binding. (C) 1998 Elsevier Science B.V. All rights reserved.