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A spectroscopic study of the interaction of isoflavones with human serum albumin

Mahesha, HG and Singh, Sandeep B and Srinivasan, N and Rao, AGA (2006) A spectroscopic study of the interaction of isoflavones with human serum albumin. In: FEBS Journal, 273 (3). pp. 451-467.

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Genistein and daidzein, the major isoflavones present in soybeans, possess a wide spectrum of physiological and pharmacological functions. The binding of genistein to human serum albumin (HSA) has been investigated by equilibrium dialysis, fluorescence measurements, CD and molecular visualization. One mole of genistein is bound per mole of HSA with a binding constant of 1.5 +/- 0.2 X 10(5) m(-1). Binding of genistein to HSA precludes the attachment of daidzein. The ability of HSA to bind genistein is found to be lost when the tryptophan residue of albumin is modified with N-bromosuccinimide. At 27 degrees C (pH 7.4), van't Hoff's enthalpy, entropy and free energy changes that accompany the binding are found to be -13.16 kcal.mol(-1), -21 cal.mol(-1)K(-1) and -6.86 kcal.mol(-1), respectively. Temperature and ionic strength dependence and competitive binding measurements of genistein with HSA in the presence of fatty acids and 8-anilino-1-naphthalene sulfonic acid have suggested the involvement of both hydrophobic and ionic interactions in the genistein-HSA binding. Binding measurements of genistein with BSA and HSA, and those in the presence of warfarin and 2,3,5-tri-iodobenzoic acid and Forster energy transfer measurements have been used for deducing the binding pocket on HSA. Fluorescence anisotropy measurements of daidzein bound and then displaced with warfarin, 2,3,5-tri-iodobenzoic acid or diazepam confirm the binding of daidzein and genistein to subdomain IIA of HSA. The ability of HSA to form ternery complexes with other neutral molecules such as warfarin, which also binds within the subdomain IIA pocket, increases our understanding of the binding dynamics of exogenous drugs to HSA.

Item Type: Journal Article
Publication: FEBS Journal
Publisher: Federation of European Biochemical Societies
Additional Information: Copyright of this article belongs to Federation of European Biochemical Societies.
Keywords: Daidzein; genistein; serum albumin;interaction studies; binding pocket.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 28 Sep 2010 07:42
Last Modified: 28 Sep 2010 07:42
URI: http://eprints.iisc.ac.in/id/eprint/31774

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