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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