Pressure dependence of human fibrinogen correlated to the conformational ?-helix to ?-sheet transition: An Fourier transform infrared study microspectroscopic study

Autor: Tzu-Feng Hsieh, Mei-Jane Li, Yen-Shan Wei, Shan-Yang Lin
Rok vydání: 2004
Předmět:
Zdroj: Biopolymers. 75:393-402
ISSN: 1097-0282
0006-3525
DOI: 10.1002/bip.20012
Popis: We used Fourier transform infrared (FTIR) microspectroscopy to investigate pressure-induced conformational changes in secondary structure of fibrinogen (FBG). Solid state FBG was compressed on a KBr pellet (1KBr method) or between two KBr pellets (2KBr method). The peak positions of the original and second-derivative ir spectra of compressed FBG samples prepared by the 1KBr method were similar to FBG sample without pressure. When FBG was prepared by the 2KBr method and pressure was increased up to 400 kg/cm2, peaks at 1625 (intermolecular β-sheet) and 1611 (β-sheet aggregates structure and/or the side-chain absorption of the tyrosine residues) cm−1 were enhanced. The peaks near 1661 (β-sheet) and 1652 (α-helix) cm−1 also exhibited a marked change with pressure. A linear correlation was found between the peak intensity ratio of 1611/1652 cm−1 (r = 0.9879) or 1625/1652 cm−1 (r = 0.9752) and applied pressure. The curve-fitted compositional changes in secondary structure of FBG also indicate that the composition of the α-helix structure (1657–1659 cm−1) was gradually reduced with the increase in compression pressure, but the composition of the β-sheet structure (1681, 1629, and 1609 cm−1) gradually increased. This indicates that pressure-induced conformational changes in FBG include not only transformations from α-helix to β-sheet structure, but also unfolding and denaturation of FBG and the formation of aggregates. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Databáze: OpenAIRE
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