Changes in primary donor hydrogen-bonding interactions in mutant reaction centers from Rhodobacter sphaeroides: Identification of the vibrational frequencies of all the conjugated carbonyl groups

Tony A. Mattioli, JoAnn C. Williams, James Paul Allen, Bruno Robert

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Abstract

Specific changes in the hydrogen-bonding states of the primary donor, P, in reaction centers from Rhodobacter sphaeroides bearing mutations near P were determined using near-infrared excited Fourier transform (FT) Raman spectroscopy. This technique, using 1064-nm excitation, provides the preresonantly enhanced vibrational spectrum of P in its reduced state selectively over the contributions of the other reaction center chromophores and protein and yields structural information concerning P and its hydrogen-bonding interactions. The mutations studied were as follows: Leu M160 → His, Leu L131 → His, the D9 double mutant (Leu M160 → His + Leu L131 → His), Phe M197 → His, and His L168 → Phe. These mutations were designed to introduce new, or to break existing, hydrogen bonds to the C9 and C2 carbonyl groups of P. On the basis of previous assignments [Mattioli, T. A., Hoffmann, A., Robert, B., Schrader, B., & Lutz, M. (1991) Biochemistry 30, 4648-4654], the FT Raman spectra of these mutants show the predicted changes in hydrogen bond interactions of P carbonyl groups with the protein. The results of this study have permitted us to unambiguously identify the C2 and C9 carbonyl vibrators of P in Rb. sphaeroides. The genetically introduced hydrogen bond interactions are discussed in terms of other physicochemical properties of P including the redox potential and electronic asymmetry in the P+ state. It is discussed that changes in protein hydrogen bonding to the conjugated carbonyl groups of P alone are not the sole factor that contributes to the sizable modifications of the P/P+ redox midpoint potentials, and that the chemical nature of the hydrogen bond donor plays a significant role in this modification.

Original languageEnglish
Pages (from-to)1636-1643
Number of pages8
JournalBiochemistry
Volume33
Issue number7
Publication statusPublished - 1994

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Rhodobacter sphaeroides
Vibrational spectra
Hydrogen Bonding
Hydrogen
Hydrogen bonds
Fourier Analysis
Mutation
Oxidation-Reduction
Proteins
Raman Spectrum Analysis
Biochemistry
Fourier transforms
Bearings (structural)
Vibrators
Chromophores
Raman spectroscopy
Raman scattering
Infrared radiation

ASJC Scopus subject areas

  • Biochemistry

Cite this

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title = "Changes in primary donor hydrogen-bonding interactions in mutant reaction centers from Rhodobacter sphaeroides: Identification of the vibrational frequencies of all the conjugated carbonyl groups",
abstract = "Specific changes in the hydrogen-bonding states of the primary donor, P, in reaction centers from Rhodobacter sphaeroides bearing mutations near P were determined using near-infrared excited Fourier transform (FT) Raman spectroscopy. This technique, using 1064-nm excitation, provides the preresonantly enhanced vibrational spectrum of P in its reduced state selectively over the contributions of the other reaction center chromophores and protein and yields structural information concerning P and its hydrogen-bonding interactions. The mutations studied were as follows: Leu M160 → His, Leu L131 → His, the D9 double mutant (Leu M160 → His + Leu L131 → His), Phe M197 → His, and His L168 → Phe. These mutations were designed to introduce new, or to break existing, hydrogen bonds to the C9 and C2 carbonyl groups of P. On the basis of previous assignments [Mattioli, T. A., Hoffmann, A., Robert, B., Schrader, B., & Lutz, M. (1991) Biochemistry 30, 4648-4654], the FT Raman spectra of these mutants show the predicted changes in hydrogen bond interactions of P carbonyl groups with the protein. The results of this study have permitted us to unambiguously identify the C2 and C9 carbonyl vibrators of P in Rb. sphaeroides. The genetically introduced hydrogen bond interactions are discussed in terms of other physicochemical properties of P including the redox potential and electronic asymmetry in the P+ state. It is discussed that changes in protein hydrogen bonding to the conjugated carbonyl groups of P alone are not the sole factor that contributes to the sizable modifications of the P/P+ redox midpoint potentials, and that the chemical nature of the hydrogen bond donor plays a significant role in this modification.",
author = "Mattioli, {Tony A.} and Williams, {JoAnn C.} and Allen, {James Paul} and Bruno Robert",
year = "1994",
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TY - JOUR

T1 - Changes in primary donor hydrogen-bonding interactions in mutant reaction centers from Rhodobacter sphaeroides

T2 - Identification of the vibrational frequencies of all the conjugated carbonyl groups

AU - Mattioli, Tony A.

AU - Williams, JoAnn C.

AU - Allen, James Paul

AU - Robert, Bruno

PY - 1994

Y1 - 1994

N2 - Specific changes in the hydrogen-bonding states of the primary donor, P, in reaction centers from Rhodobacter sphaeroides bearing mutations near P were determined using near-infrared excited Fourier transform (FT) Raman spectroscopy. This technique, using 1064-nm excitation, provides the preresonantly enhanced vibrational spectrum of P in its reduced state selectively over the contributions of the other reaction center chromophores and protein and yields structural information concerning P and its hydrogen-bonding interactions. The mutations studied were as follows: Leu M160 → His, Leu L131 → His, the D9 double mutant (Leu M160 → His + Leu L131 → His), Phe M197 → His, and His L168 → Phe. These mutations were designed to introduce new, or to break existing, hydrogen bonds to the C9 and C2 carbonyl groups of P. On the basis of previous assignments [Mattioli, T. A., Hoffmann, A., Robert, B., Schrader, B., & Lutz, M. (1991) Biochemistry 30, 4648-4654], the FT Raman spectra of these mutants show the predicted changes in hydrogen bond interactions of P carbonyl groups with the protein. The results of this study have permitted us to unambiguously identify the C2 and C9 carbonyl vibrators of P in Rb. sphaeroides. The genetically introduced hydrogen bond interactions are discussed in terms of other physicochemical properties of P including the redox potential and electronic asymmetry in the P+ state. It is discussed that changes in protein hydrogen bonding to the conjugated carbonyl groups of P alone are not the sole factor that contributes to the sizable modifications of the P/P+ redox midpoint potentials, and that the chemical nature of the hydrogen bond donor plays a significant role in this modification.

AB - Specific changes in the hydrogen-bonding states of the primary donor, P, in reaction centers from Rhodobacter sphaeroides bearing mutations near P were determined using near-infrared excited Fourier transform (FT) Raman spectroscopy. This technique, using 1064-nm excitation, provides the preresonantly enhanced vibrational spectrum of P in its reduced state selectively over the contributions of the other reaction center chromophores and protein and yields structural information concerning P and its hydrogen-bonding interactions. The mutations studied were as follows: Leu M160 → His, Leu L131 → His, the D9 double mutant (Leu M160 → His + Leu L131 → His), Phe M197 → His, and His L168 → Phe. These mutations were designed to introduce new, or to break existing, hydrogen bonds to the C9 and C2 carbonyl groups of P. On the basis of previous assignments [Mattioli, T. A., Hoffmann, A., Robert, B., Schrader, B., & Lutz, M. (1991) Biochemistry 30, 4648-4654], the FT Raman spectra of these mutants show the predicted changes in hydrogen bond interactions of P carbonyl groups with the protein. The results of this study have permitted us to unambiguously identify the C2 and C9 carbonyl vibrators of P in Rb. sphaeroides. The genetically introduced hydrogen bond interactions are discussed in terms of other physicochemical properties of P including the redox potential and electronic asymmetry in the P+ state. It is discussed that changes in protein hydrogen bonding to the conjugated carbonyl groups of P alone are not the sole factor that contributes to the sizable modifications of the P/P+ redox midpoint potentials, and that the chemical nature of the hydrogen bond donor plays a significant role in this modification.

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