Conformational changes of serum albumin upon complexation with amphiphilic drug imipramine hydrochloride

Journal Article

Khan, Malik Abdul Rub, Javed Masood Khan, Zahid Yaseen, Rizwan Hasan . 2012

• Issue Number: 3
• Volume Number: 3
• Pages: 207-215

Publication Abstract

 Imipramine hydrochloride (IMP) is a cationic amphiphilic molecule belonging to the antidepressant category of drugs. Here we report the interaction of IMP with serum albumins (i.e., human (HSA) and bovine (BSA)) using various biophysical methods. Absorption spectroscopy provides qualitative information about the interaction and complex formation between IMP and serum albumins. The binding parameters and the corresponding thermodynamic parameters have been estimated by fluorescence quenching method. The results revealed that hydrophobic forces were the predominant intermolecular forces between serum albumins and IMP. The quenching rate constant (kq) values decrease with increase in temperature which indicates a static quenching procedure. At very low concentrations of drug, the conformational changes in HSA/BSA due to interaction were investigated by circular dichroism (CD). For different molar ratios of protein and drug, the farUV CD spectra showed an increase in alpha-helicity of serum albumins with the increment in alpha-helical structural content being slightly higher for IMP-BSA complex.