Understanding the structure-function relationships of hemoglobin (Hb) is of great biomedical significance. The two-state allosteric model of Monod, Wyman, and Changeux (MWC) has long been used to provide a description of a wide variety of structural, equilibrium and kinetic data on cooperative oxygen binding to Hb. Recent work performed under the above-mentioned parent grant has challenged the fundamental assumption underlying the MWC model and stating that oxygen affinity is primarily determined by the quaternary structure. Work performed in my laboratory shows that an extended MWC allosteric model is required to fully account for the variation of oxygen binding isotherms induced by allosteric effectors. This proposal aims at investigating features of the extended MWC model suggested by our ligand binding studies using a combined experimental and computational approach designed to complement our previous work using HbA hybrids. It features a high-resolution FLN laser spectroscopy experimental approach which will be used - not only for the acquisition of vibronically-resolved spectra - but also to perform pressure studies. The essential originality of this proposal resides in the application of a spectroscopic technique designed to monitor hydrostatic pressure as a thermodynamic parameter combined to a computational approach aimed at modeling the effect of binding allosteric effectors on the Hb tertiary and quaternary structure. The Hungarian laboratory (Fidy) will carry out the high-resolution spectroscopy experiments and pressure studies as well as the computational work. The synthesis of the required HbA hybrids will be done in my laboratory (Yonetani) as well as the FT-Raman experiments.
|Laberge, Monique; Kovesi, Istvan; Yonetani, Takashi et al. (2006) Normal mode analysis of the horseradish peroxidase collective motions: correlation with spectroscopically observed heme distortions. Biopolymers 82:425-9|
|Schay, Gusztav; Smeller, Laszlo; Tsuneshige, Antonio et al. (2006) Allosteric effectors influence the tetramer stability of both R- and T-states of hemoglobin A. J Biol Chem 281:25972-83|
|Kovesi, I; Schay, G; Yonetani, T et al. (2006) High pressure reveals that the stability of interdimeric contacts in the R- and T-state of HbA is influenced by allosteric effectors: Insights from computational simulations. Biochim Biophys Acta 1764:516-21|
|Laberge, Monique; Kovesi, Istvan; Yonetani, Takashi et al. (2005) R-state hemoglobin bound to heterotropic effectors: models of the DPG, IHP and RSR13 binding sites. FEBS Lett 579:627-32|
|Laberge, Monique; Yonetani, Takashi; Fidy, Judit (2003) Normal coordinate structural decomposition of the heme distortions of hemoglobin in various quaternary states and bound to allosteric effectors. Mol Divers 7:15-23|