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Interaction of cucurbitacins with human serum albumin: Thermodynamic characteristics and influence on the binding of site specific ligands

Paper ID Volume ID Publish Year Pages File Format Full-Text
29977 44449 2009 7 PDF Available
Title
Interaction of cucurbitacins with human serum albumin: Thermodynamic characteristics and influence on the binding of site specific ligands
Abstract

Cucurbitacins (Cuc) are cytotoxic oxygenated triterpenes. Their binding to albumin may control their diffusion and consequently their biological effects. The specific binding site of Cuc to albumin is important to be defined as it could determine some of the drug interactions of the compounds. This paper deals with the interaction between human serum albumin and a series of four cucurbitacins (B, D, E and I) measured by fluorescence and circular dichroism spectroscopies. Cuc B and E at C25, are the acetylated forms of Cuc D and I. The binding parameters (Ka and n) of Cuc B, D and E to albumin were determined at 288, 293, 298 and 303 K. Cuc B possesses the higher binding constant (Ka) values followed by Cuc E and D. The thermodynamic parameters ΔH, ΔG and ΔS were calculated. They indicated hydrophobic and electrostatic interactions for Cuc B, hydrophobic interaction for Cuc E, hydrophobic and hydrogen bond interactions for Cuc D. In addition to bilirubin, Cuc B, D, and E increased the binding constant values for warfarin to albumin, whereas they did not affect the binding of other ligands of site I such as chloroform and salicylate. The increase of the Ka values of warfarin and bilirubin was associated with an increase of the binding constant value of cucurbitacin to albumin. Cuc I did not bind to albumin and could be considered less capable to affect the interaction of ligands to albumin than Cuc B, D and E. CD spectra indicated that Cuc binding to HSA was not associated with substantial structural changes of the protein.

Keywords
Human serum albumin; Cucurbitacin; Site markers; Binding parameters; Thermodynamic parameters
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Interaction of cucurbitacins with human serum albumin: Thermodynamic characteristics and influence on the binding of site specific ligands
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 95, Issue 3, 3 June 2009, Pages 189–195
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us