title: Combined multispectroscopic and molecular docking investigation on the interaction between strictosamide and human serum albumin.
abstract: The interaction between strictosamide (STM) and human serum albumin (HSA) was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, circular dichroism spectroscopy and molecular modeling under physiological pH 7.4. STM effectively quenched the intrinsic fluorescence of HSA via static quenching. The binding site number n and apparent binding constant K(a) were determined at different temperatures by fluorescence quenching. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) for the reaction were calculated as -3.01 kJ/mol and 77.75 J/mol per K, respectively, which suggested that the hydrophobic force played major roles in stabilizing the HSA-STM complex. The distance r between donor and acceptor was obtained to be 4.10 nm according to Förster's theory. After the addition of STM, the synchronous fluorescence and three-dimensional fluorescence spectral results showed that the hydrophobicity of amino acid residues increased and the circular dichroism spectral results showed that the α-helix content of HSA decreased (from 61.48% to 57.73%). These revealed that the microenvironment and conformation of HSA were changed in the binding reaction. Furthermore, the study of molecular modeling indicated that STM could bind to site I of HSA and the hydrophobic interaction was the major acting force, which was in agreement with the binding mode study.
authors: Department of Cell Biology, College of Life Science and Technology, Jinan University, Guangzhou 510632, People's Republic of China. tphl@jnu.edu.cn
authors: Hanlin
authors: H
authors: Pu
authors: Hua
authors: H
authors: Jiang
authors: Rongrong
authors: R
authors: Chen
mesh_terms: D002942:Circular Dichroism; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D014748:Vinca Alkaloids / Q000737:chemistry*
chemical_list: D012709:Serum Albumin; D014748:Vinca Alkaloids; C539462:strictosamide
keywords: Circular dichroism spectroscopy; Fluorescence quenching; Human serum albumin; Molecular modeling; Strictosamide