The long-term objective of this project is to understand the structure-function relationship in oxygen-linked respiratory hemoproteins such as myoglobin and hemoglobin by means of chemical modifications of specific molecular moieties of hemoproteins and characterization of physical properties and biochemical and physiological functions of such modified hemoproteins. Metal-substituted myoglobins and hemoglobins, particularly cobalt-porphyrin-substituted myoglobins and hemoglobins will be prepared and the mode of their interactions which diatomic ligands such as oxygen, carbon monoxide, and mitric oxide will be elucidated by thermodynamic and kinetic measurements and spectroscopic methods, especially EPR, NMR, resonance Raman, and Moessbauer spectroscopic techniques. Such investigations will allow us to identify stereochemical and electronic factors which affect kinetic and thermodynamic properties of ligand interaction, associated changes in the coordination of the prosthetic groups and the tertiary and quaternary structures of the molecules, to understand the molecular mechanism of reversible ligand binding, ligand activation, and ligand- and effector-linked subunit cooperativity and allostery in these respiratory hemoproteins, and eventually to design artificial hemoproteins which may be used as effective substitutes for natural hemoproteins of biomedical importance. Therefore, the proposed project sharply focuses on the physiological and biomedical vital aspects of oxygen delivery and utilization in tissues. Since the molecular mechanism of hemoglobin cooperativity and allostery will undoubtedly provide a useful clue to understand the vital regulatory role of allosteric enzymes in metabolism and since hemoprotein-nitric oxide complexes are frequently observed as intermediates/byproducts in metabolism of nitrogenous carcinogens, the proposed project will have wide-ranged biomedical implications.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Method to Extend Research in Time (MERIT) Award (R37)
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University of Pennsylvania
Schools of Medicine
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Laberge, Monique; Yonetani, Takashi (2008) Molecular dynamics simulations of hemoglobin A in different states and bound to DPG: effector-linked perturbation of tertiary conformations and HbA concerted dynamics. Biophys J 94:2737-51
Egawa, Tsuyoshi; Tsuneshige, Antonio; Suematsu, Makoto et al. (2007) Method for determination of association and dissociation rate constants of reversible bimolecular reactions by isothermal titration calorimeters. Anal Chem 79:2972-8
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
Suganuma, Kazuhiro; Tsukada, Kosuke; Kashiba, Misato et al. (2006) Erythrocytes with T-state-stabilized hemoglobin as a therapeutic tool for postischemic liver dysfunction. Antioxid Redox Signal 8:1847-55
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
Yokoyama, Takeshi; Neya, Saburo; Tsuneshige, Antonio et al. (2006) R-state haemoglobin with low oxygen affinity: crystal structures of deoxy human and carbonmonoxy horse haemoglobin bound to the effector molecule L35. J Mol Biol 356:790-801
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
Nagatomo, Shigenori; Nagai, Masako; Mizutani, Yasuhisa et al. (2005) Quaternary structures of intermediately ligated human hemoglobin a and influences from strong allosteric effectors: resonance Raman investigation. Biophys J 89:1203-13
Tsuneshige, Antonio; Kanaori, Kenji; Samuni, Uri et al. (2004) Semihemoglobins, high oxygen affinity dimeric forms of human hemoglobin respond efficiently to allosteric effectors without forming tetramers. J Biol Chem 279:48959-67

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