Resonance Raman investigation of nitric oxide bonding in nitrosylhemoglobin A and -myoglobin: detection of bound nitrogen-oxygen stretching and iron-nitric oxide stretching vibrations from the hexacoordinated nitric oxide-heme complex

Tsubaki, Motonari; Yu, Nai‐Teng

doi:10.1021/bi00535a005

Cited by 78 publications

(48 citation statements)

References 20 publications

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“…2). For these cases, the frequency for reaching the crossing point is much larger because Fe-CO, Fe-NO and Fe-O 2 frequencies are typically Ϸ500 cm Ϫ1 (52,53). If the ligand is not in a bound state, the attempt frequency for approach to the TS corresponds to heme doming with a frequency of Ϸ50-100 cm Ϫ1 (54)(55)(56).…”

Section: Discussionmentioning

confidence: 99%

Spin-dependent mechanism for diatomic ligand binding to heme

Franzen

2002

Proc. Natl. Acad. Sci. U.S.A.

105

134

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The nature of diatomic ligand recombination in heme proteins is elucidated by using a Landau-Zener model for the electronic coupling in the recombination rate constant. The model is developed by means of explicit potential energy surfaces calculated by using density functional theory (DFT). The interaction of all possible spin states of the three common diatomic ligands, CO, NO, and O2, and high-spin heme iron is compared. The electronic coupling, rebinding barrier, and Landau-Zener force terms can be obtained and used to demonstrate significant differences among the ligands. In particular the intermediate spin states of NO (S ‫؍‬ 3͞2) and O2 (S ‫؍‬ 1) are shown to be bound states. Rapid recombination occurs from these bound states in agreement with experimental data. The slower phases of O2 recombination can be explained by the presence of two higher spin states, S ‫؍‬ 2 and S ‫؍‬ 3, which have a small and relatively large barrier to ligand recombination, respectively. By contrast, the intermediate spin state for CO is not a bound state, and the only recombination pathway for CO involves direct recombination from the S ‫؍‬ 2 state. This process is significantly slower according to the Landau-Zener model. Quantitative estimates of the parameters used in the rate constants provide a complete description that explains rebinding rates that range from femtoseconds to milliseconds at ambient temperature.T he binding of diatomic ligands to heme has been studied for over 100 years (1). The dissociation of carbon monoxide (CO), nitric oxide (NO), and oxygen (O 2 ) from the iron of heme occurs by both a thermal and photolytic process (2-4). In the case of flash photolysis, the fate of the ligand depends on the competition between the intrinsic (or geminate) recombination rate constant and protein relaxation in a docking site roughly 3.5 Å from the iron as well as ligand escape from the protein (5-8). Recombination of these ligands occurs by the reverse of the thermal process. The time dependence of recombination serves as a probe of the intrinsic properties of the diatomic ligand-iron bond formation and dynamic processes that occur in the protein that surrounds the heme cofactor (9-11). The startlingly different recombination dynamics of CO, NO, and O 2 have been attributed to spin states in earlier work (3,12). In the present study, the ground state potential energy surfaces for the potential energy surfaces of all possible spin states are calculated by using density functional theory (DFT) and compared within the context of a Landau-Zener (L-Z) model for the intrinsic recombination process of each of the ligands. The observed recombination kinetics of CO, NO, and O 2 can be influenced by protein dynamics if the intrinsic recombination rate constant is slower than these dynamics (10,(13)(14)(15)(16). When a combination of temperature and viscosity dependence is used, the general time scale for the intrinsic rate constants can be extracted, and it is these rate constants that are compared in the present work.The rebindin...

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Section: Discussionmentioning

confidence: 99%

Spin-dependent mechanism for diatomic ligand binding to heme

Franzen

2002

Proc. Natl. Acad. Sci. U.S.A.

105

134

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“…550 and ca. 1610 cm -1 (19,20,29,30). In favorable cases, the Fe-N-O bending vibration can also be detected, at ca.…”

Section: Spectralmentioning

confidence: 95%

FeNO Structure in Distal Pocket Mutants of Myoglobin Based on Resonance Raman Spectroscopy

et al. 2003

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/npsi/ctrl?action=rtdoc&an=12338206&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=12338206&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

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“…39 In RR spectra, 6-coordinate {FeNO} 7 species display ν 3 and ν 10 porphyrin core modes at 1500 and 1630 cm −1 , respectively, while, in 5-coordinated species, these same modes are observed 5 to 10 cm −1 higher. 36,[40][41][42] The ν(Fe-NO) and ν(NO) modes can be identified with isotopic labeling and provide further confirmation of the coordination number of the heme iron. Specifically, the proximal ligand trans to the nitrosyl has been shown to intensify the back-donation of Fe d π electrons into the nitrosyl π* orbital, thus resulting in higher ν(Fe-NO) and lower ν(NO) for 6-coordinate species.…”

Section: Spectroscopic Signatures Of Heme Iron-nitrosyl Complexesmentioning

confidence: 99%

Spectroscopic characterization of heme iron–nitrosyl species and their role in NO reductase mechanisms in diiron proteins

Moënne‐Loccoz

2007

Nat. Prod. Rep.

121

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Nitric oxide (NO) plays an important role in cell signalling and in the mammalian immune response to infection. On its own, NO is a relatively inert radical, and when it is used as a signalling molecule, its concentration remains within the picomolar range. However, at infection sites, the NO concentration can reach the micromolar range, and reactions with other radical species and transition metals lead to a broad toxicity. Under aerobic conditions, microorganisms cope with this nitrosative stress by oxidizing NO to nitrate (NO 3 − ). Microbial hemoglobins play an essential role in this NO-detoxifying process. Under anaerobic conditions, detoxification occurs via a 2-electron reduction of two NO molecules to N 2 O. In many bacteria and archaea, this NOreductase reaction is catalyzed by diiron proteins. Despite the importance of this reaction in providing microorganisms with a resistance to the mammalian immune response, its mechanism remains ill-defined. Because NO is an obligatory intermediate of the denitrification pathway, respiratory NO reductases also provide resistance to toxic concentrations of NO. This family of enzymes is the focus of this review. Respiratory NO reductases are integral membrane protein complexes that contain a norB subunit evolutionarily related to subunit I of cytochrome c oxidase (CcO). NorB anchors one high-spin heme b 3 and one non-heme iron known as Fe B , i.e., analogous to Cu B in CcO. A second group of diiron proteins with NO-reductase activity is comprised of the large family of soluble flavoprotein A found in strict and facultative anaerobic bacteria and archaea. These soluble detoxifying NO reductases contain a non-heme diiron cluster with a Fe-Fe distance of 3.4 Å and are only briefly mentioned here as a promising field of research. This article describes possible mechanisms of NO reduction to N 2 O in denitrifying NO-reductase (NOR) proteins and critically reviews recent experimental results. Relevant theoretical model calculations and spectroscopic studies of the NO-reductase reaction in heme/copper terminal oxidases are also overviewed.

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Resonance Raman investigation of nitric oxide bonding in nitrosylhemoglobin A and -myoglobin: detection of bound nitrogen-oxygen stretching and iron-nitric oxide stretching vibrations from the hexacoordinated nitric oxide-heme complex

Cited by 78 publications

References 20 publications

Spin-dependent mechanism for diatomic ligand binding to heme

Spin-dependent mechanism for diatomic ligand binding to heme

FeNO Structure in Distal Pocket Mutants of Myoglobin Based on Resonance Raman Spectroscopy

Spectroscopic characterization of heme iron–nitrosyl species and their role in NO reductase mechanisms in diiron proteins

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