title: [Spectroscopic study on the conformational change of silk fibroin in methanol-water mixtures].
abstract: A combinational study of circular dichroism, intrinsic fluorescence of protein and exogenous fluorescence probe of ANS was made to investigate the conformational change of silk fibroin in methanol-water mixtures as well as the mechanism. The spectral results showed that small hydrophobic regions were formed in silk fibroin in methanol-water mixtures at the concentration lower than 30% (V/V) via hydrophobic interaction, which was decreased at higher methanol content due to a structural transition of silk fibroin from random coil to beta-sheet. The conformational change of silk fibroin was found to be of a close relationship with the microstructure of the solvent and to be determined by the interaction between the peptide unit of silk fibroin and the cluster of the mixed solvent. Methanol-water mixture at low concentration had little effect on the solvation of the peptide unit and the conformation of silk fibroin, as a consequence of the fact that the inherent water structure was conserved. The transition from the tetrahedral-like water structure to the chain-like methanol structure, due to the increasing concentration of methanol, induced the conformational change of silk fibroin to eliminate the contact of peptide unit with the solvent molecular.
authors.affiliation: College of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China. malinzju@gxu.edu.com
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
authors.forename: Wei-ren
authors.initials: WR
authors.lastname: He
authors.forename: Ai-min
authors.initials: AM
authors.lastname: Huang
authors.forename: Li-shuo
authors.initials: LS
authors.lastname: Li
authors.forename: Zhang-fa
authors.initials: ZF
authors.lastname: Tong
authors.forename: Qiao-na
authors.initials: QN
authors.lastname: Wei
authors.forename: Zi-lun
authors.initials: ZL
authors.lastname: Huang
mesh_terms: D000818:Animals; D005349:Fibroins / Q000737:chemistry*; D000432:Methanol; D008968:Molecular Conformation; D012997:Solvents; D013057:Spectrum Analysis; D014867:Water
chemical_list: D012997:Solvents; D014867:Water; D005349:Fibroins; D000432:Methanol