Characterization of cooperative conformational transitions by Fourier transform infrared spectroscopy : application to phospholipid binary mixtures

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1139/v85-319
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Name affiliation
  1. National Research Council of Canada
FormatText, Article
Journal titleCanadian Journal of Chemistry
ISSN0008-4042
1480-3291
Volume63
Issue7
Pages1925–1932
Abstract
Temperature-induced cooperative conformational transitions in biopolymers may be examined in aqueous solution by the use of Fourier transform infrared spectroscopy. The transition is described in terms of a two-state model with a fractional population parameter (which describes the degree of transition at various values intermediate between the two limiting cases) that can be generated by a least-squares technique. This procedure allows for calculation of a conformational index without assuming a linear dependence of the infrared parameter on the extent of transition. Calculations based on the Zimm–Bragg theory of cooperative conformational transitions allow thermodynamic quantities to be derived using the conformational index in conjunction with calorimetric measurements.The method is illustrated with data from the gel/liquid-crystalline phase transitions of binary phospholipid vesicles where the use of isotopic substitution allows the conformation of each component of the binary mixture to be independently monitored. The data suggest the coexistence of well-defined structural domains of phospholipid as well as the preferential clustering of one of the lipid components at the interface between the two phases.
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LanguageEnglish
Peer reviewedYes
NPARC number23001393
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