Structural and Functional Significance of Inhomogeneous Line Broadening of Band III in Hemoglobin and Fe-Mn Hybrid Hemoglobins

M. D. Chavez; S. H. Courtney; M. R. Chance; D. Kiula; J. Nocek; B. M. Hoffman; J. M. Friedman; M. R. Ondrias

doi:10.1021/bi00472a014

Structural and Functional Significance of Inhomogeneous Line Broadening of Band III in Hemoglobin and Fe-Mn Hybrid Hemoglobins

M. D. Chavez, S. H. Courtney, M. R. Chance, D. Kiula, J. Nocek, B. M. Hoffman, J. M. Friedman, M. R. Ondrias

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Abstract

Near-infrared spectra of hemoglobin and Fe-Mn hybrid hemoglobins have been obtained at cryogenic temperatures. The charge-transfer (a_2u(π)→d_zy) transition at ~760 nm (band III) has been found to be a conformationally sensitive indicator of the heme-pocket geometry in these species. Temperature, protein tertiary and quaternary structure, chain heterogeneity, and ligand rebinding subsequent to CO photolysis all affect the line width and position of this transition. We conclude that the overall line shape of band III is derived from both subunit heterogeneity and conformational disorder within each subunit. A model is suggested that relates the observed pH dependence of the kinetic hole burning due to ligand rebinding to specific structural parameters of the proximal heme pocket that influence both the peak position and the inhomogeneous line shape of band III.

Original language	English (US)
Pages (from-to)	4844-4852
Number of pages	9
Journal	Biochemistry
Volume	29
Issue number	20
DOIs	https://doi.org/10.1021/bi00472a014
State	Published - May 1 1990
Externally published	Yes

ASJC Scopus subject areas

Biochemistry

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title = "Structural and Functional Significance of Inhomogeneous Line Broadening of Band III in Hemoglobin and Fe-Mn Hybrid Hemoglobins",

abstract = "Near-infrared spectra of hemoglobin and Fe-Mn hybrid hemoglobins have been obtained at cryogenic temperatures. The charge-transfer (a2u(π)→dzy) transition at ~760 nm (band III) has been found to be a conformationally sensitive indicator of the heme-pocket geometry in these species. Temperature, protein tertiary and quaternary structure, chain heterogeneity, and ligand rebinding subsequent to CO photolysis all affect the line width and position of this transition. We conclude that the overall line shape of band III is derived from both subunit heterogeneity and conformational disorder within each subunit. A model is suggested that relates the observed pH dependence of the kinetic hole burning due to ligand rebinding to specific structural parameters of the proximal heme pocket that influence both the peak position and the inhomogeneous line shape of band III.",

author = "Chavez, {M. D.} and Courtney, {S. H.} and Chance, {M. R.} and D. Kiula and J. Nocek and Hoffman, {B. M.} and Friedman, {J. M.} and Ondrias, {M. R.}",

year = "1990",

month = may,

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doi = "10.1021/bi00472a014",

language = "English (US)",

volume = "29",

pages = "4844--4852",

journal = "Biochemistry",

issn = "0006-2960",

publisher = "American Chemical Society",

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TY - JOUR

T1 - Structural and Functional Significance of Inhomogeneous Line Broadening of Band III in Hemoglobin and Fe-Mn Hybrid Hemoglobins

AU - Chavez, M. D.

AU - Courtney, S. H.

AU - Chance, M. R.

AU - Kiula, D.

AU - Nocek, J.

AU - Hoffman, B. M.

AU - Friedman, J. M.

AU - Ondrias, M. R.

PY - 1990/5/1

Y1 - 1990/5/1

N2 - Near-infrared spectra of hemoglobin and Fe-Mn hybrid hemoglobins have been obtained at cryogenic temperatures. The charge-transfer (a2u(π)→dzy) transition at ~760 nm (band III) has been found to be a conformationally sensitive indicator of the heme-pocket geometry in these species. Temperature, protein tertiary and quaternary structure, chain heterogeneity, and ligand rebinding subsequent to CO photolysis all affect the line width and position of this transition. We conclude that the overall line shape of band III is derived from both subunit heterogeneity and conformational disorder within each subunit. A model is suggested that relates the observed pH dependence of the kinetic hole burning due to ligand rebinding to specific structural parameters of the proximal heme pocket that influence both the peak position and the inhomogeneous line shape of band III.

AB - Near-infrared spectra of hemoglobin and Fe-Mn hybrid hemoglobins have been obtained at cryogenic temperatures. The charge-transfer (a2u(π)→dzy) transition at ~760 nm (band III) has been found to be a conformationally sensitive indicator of the heme-pocket geometry in these species. Temperature, protein tertiary and quaternary structure, chain heterogeneity, and ligand rebinding subsequent to CO photolysis all affect the line width and position of this transition. We conclude that the overall line shape of band III is derived from both subunit heterogeneity and conformational disorder within each subunit. A model is suggested that relates the observed pH dependence of the kinetic hole burning due to ligand rebinding to specific structural parameters of the proximal heme pocket that influence both the peak position and the inhomogeneous line shape of band III.

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JO - Biochemistry

JF - Biochemistry

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Structural and Functional Significance of Inhomogeneous Line Broadening of Band III in Hemoglobin and Fe-Mn Hybrid Hemoglobins

Abstract

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