Electron nuclear double resonance and electron paramagnetic resonance study on the structure of the NO-ligated heme alpha 3 in cytochrome c oxidase.

LoBrutto, Russell; Wei, Yau‐Huei; Mascarenhas, Rita; Scholes, Charles P.; King, Tsoo E.

doi:10.1016/s0021-9258(18)32198-7

Cited by 48 publications

(22 citation statements)

References 37 publications

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“…Coupling to the directly coordinated and remote nitrogen atoms of bound imidazoles is not detected by ESEEM spectroscopy since no new components were observed upon substitution of imidazole for pyridine. ENDOR spectroscopy indicates a 16-MHz coupling for the directly coordinated, or imino, nitrogen of imidazole in nitrosyl heme proteins and NO heme model complexes (LoBrutto et al, 1983). Couplings of this magnitude do not give rise to envelope modulations in our spin-echo experiments (Mims & Peisach, 1978).…”

Section: Resultsmentioning

confidence: 60%

“…Electron paramagnetic resonance spectroscopy has been extensively used in studies of high-and low-spin ferric heme proteins (Blumberg et al, 1968;Peisach et al, 1971;Chevion et al, 1977;Hollenberg et al, 1980;Palmer, 1985) and ferrous nitrosyl heme proteins (Kon, 1968;Yonetani et al, 1972;Chevion et al, 1977; Hille et a!., 1979; Morse & Chan, 1980;Hori et al, 1981;LoBrutto et al, 1983). These studies, in general, have addressed the identity of axial ligands to heme iron.…”

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confidence: 99%

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Electron-nuclear coupling in nitrosyl heme proteins and in nitrosyl ferrous and oxy cobaltous tetraphenylporphyrin complexes

Magliozzo¹,

McCracken²,

Peisach³

1987

Biochemistry

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Electron spin echo envelope modulation (ESEEM) spectroscopy has been used to study electron-nuclear interactions in the following isoelectronic S = 1/2 complexes: NO-FeII(TPP) (TPP = tetraphenylporphyrin) with and without axial nitrogenous base, nitrosylhemoglobin in R and T states, and O2-CoII(TPP) with and without axial base. Only the porphyrin pyrrole nitrogens contribute to the ESEEM of the 6-coordinate nitrosyl FeII(TPP) complexes, nitrosylhemoglobin (R-state), and the nitrosyl complexes of alpha and beta chains. Pyrrole nitrogens in the 5-coordinate complex NO-FeII(TPP) are coupled too weakly to unpaired spin and therefore do not contribute to the ESEEM. A partially saturated T-state nitrosylhemoglobin does not exhibit echo envelope modulations characteristic of 6-coordinate nitrosyl species, which confirms that the proximal imidazole bond to heme iron is disrupted. Study of 6-coordinate O2-CoII(TPP)(L) complexes (L = nitrogenous base) using 14N- and 15N-labeled ligands and porphyrins enabled a detailed analysis of coupling parameters for both pyrrole and axial nitrogens. The pyrrole 14N coupling frequencies are similar to those in NO-FeII(TPP)(L). The Fermi contact couplings for axially bound nitrogen, calculated from simulation of ESEEM spectra for a series of O2-CoII(TPP)(L) complexes (L = pyridine, 4-picoline, 4-cyanopyridine, 4-carboxypyridine, and 1-, 2-, and 4-methylimidazole) illustrate a trend toward stronger hyperfine interactions with weaker bases.

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Section: Resultsmentioning

confidence: 60%

mentioning

confidence: 99%

Electron-nuclear coupling in nitrosyl heme proteins and in nitrosyl ferrous and oxy cobaltous tetraphenylporphyrin complexes

Magliozzo¹,

McCracken²,

Peisach³

1987

Biochemistry

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“…The EPR and ENDOR investigations have yielded information about the g-tensor principal components, nitrogen hyperfine couplings of axial ligands, and proton interactions of the porphyrin moiety and surrounding protein. The reported hyperfine couplings for the nitrogen of nitric oxide and for the coordinated nitrogen of the proximal histidine (or imidazole in model complexes) of 15-20 MHz are large enough to be well observable in ENDOR 20,21 and even partially in the EPR spectra of frozen solutions. 3,12,19 ENDOR technique specifically demonstrates high resolution in the study of weakly coupled protons.…”

Section: Introductionmentioning

confidence: 92%

“…Due to this property, EPR spectroscopy has been crucial in the study of NO interaction with hemoproteins 1,2,12-14 as well as its physiological role. 15,16 A number of EPR and electronnuclear double-resonance (ENDOR) studies of NO-hemoglo- bin, its isolated Rand βsubunits, myoglobin, and several model compounds such as NO-ligated Fe-tetraphenylporphyrin (TPP) with imidazole as sixth axial ligand were performed in frozen solutions 2,3,12,13, [17][18][19][20][21][22] as well as in single crystals [23][24][25][26] aiming at an elucidation of structural details of the NOhemoglobin interactions. While these studies have contributed to the understanding of the electronic structure and geometry of the NO-bound species, several details, especially those concerning changes upon R-T-"like" transitions, still remain unclear.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Bimodal Coordination Structure in Nitrosyl Heme Complexes through Hyperfine Couplings with Pyrrole and Protein Nitrogens

et al. 1999

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Orientation-selected three-pulse ESEEM experiments have been performed on a series of nitrosyl hemoproteins: HbNO in its two quaternary (R/T) states, the isolated NO-ligated α(β)-chains of hemoglobin, two hybrids of hemoglobin with asymmetrically ligated α(β)-chains, NO−myoglobin, and NO−Fe2+(TPP)−imidazole model complexes. The ESEEM spectra of the native complexes clearly revealed the contribution from two conformational states of the NO−heme group. At 4.2 K the αNO and βNO chains were found in an almost pure state, i.e., 80% “state I” and 90% “state II”, respectively. These results correlate well with the two-conformation model of 6-coordinated NO−heme complexes proposed earlier from the evaluation of temperature-dependent EPR/ENDOR spectra (Morse, R. H.; Chan, S. I. J. Biol. Chem. 1980 , 255, 7876. Hüttermann, J.; Burgard, C.; Kappl, R. J. Chem. Soc., Faraday Trans. 1994, 90, 3077). Application of two-dimensional ESEEM spectroscopy (HYSCORE) to the isolated αNO and βNO chains allowed the characterization of the pyrrole nitrogen HFI in both conformations. A third nitrogen coupling was identified in the HYSCORE of the βNO chain. It was tentatively assigned to the Nε nitrogen of distal His E7 which is suggested to form a hydrogen bond to the NO group in the axial NO−heme conformation. These findings support the proposal that the variation of binding geometry in two states of NO−heme is controlled by the heme's protein surrounding and could provide an important contribution to the discussion on the physiological role of NO related to its interactions with protein metal centers.

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“…8 The paramagnetic nature of the Fe(II) nitrosyl-heme complexes made EPR spectroscopic technique an attractive tool in the investigation of their structural and electronic properties in frozen solutions and single crystals. 6,[9][10][11][12][13][14][15][16][17][18][19][20] The NO-heme complex may be five or six-coordinated. In the six-coordinated nitrosyl hemoproteins often two coexisting species with different symmetry of their g-factor are present in solution.…”

Section: Introductionmentioning

confidence: 99%

Revisiting the nitrosyl complex of myoglobin by high-field pulse EPR spectroscopy and quantum mechanical calculations

Radoul

Sundararajan

Потапов

et al. 2010

Phys. Chem. Chem. Phys.

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The binding of NO to reduced myoglobin in solution results in the formation of two paramagnetic nitrosyl myoglobin (MbNO) complexes: one with a rhombic g-factor and the other with an axial one, referred to as the R- and A-forms. In spite of past extensive studies of MbNO by crystallography, spectroscopy and quantum chemical calculations it is still not clear what factors determine the appearance of the two forms. In this work we applied a combination of state of the art quantum chemical calculations and high field pulsed EPR spectroscopy (W-band, 3.4 T/95 GHz) to further characterize the two forms. Specifically, we have used (1)H and (2)H electron-nuclear double resonance (ENDOR) spectroscopy to identify and characterize the H-bond to the NO, and hyperfine sub-level correlation (HYSCORE) spectroscopy to determine the hyperfine and quadrupole interactions of the Fe(ii) coordinated (14)N of the proximal histidine (14)N(His93). The calculations employed quantum mechanics (QM), particularly density functional theory (DFT) methods in combination with molecular mechanics (MM) force-field to model the protein environment. Through QM/MM calculations of the EPR parameters we have explored their dependence on several geometrical factors of the Fe-NO bond and found those that reproduce the best experimental results. The spread of the W-band EPR spectrum of MbNO due to the g-anisotropy is large and there is a significant part of the spectrum where the R-form is the sole contributor. This allowed us to resolve some new characteristics of the R-form: (i) a NO-H hydrogen bond has been detected and characterized and through QM/MM calculations has been unambiguously assigned to (epsilon2)H(His64). (ii) The complete hyperfine and quadrupole interactions of (14)N(His93) have been determined and correlated with structural parameters again using QM/MM calculations. The agreement between the experimental results and calculations varied between excellent and good, depending on the EPR parameter in question. As for the more elusive A-form, the results only suggest that it does have a (14)N(His93) ligand with a hyperfine comparable to that of the R-form and it has less hydrogen bonding interaction with His(64). The calculations also established the orientation of the principal g-values, finding that they are closely related to the orientation of the NO bond. This information is essential for deriving structural information from the experimental orientation selective HYSCORE and ENDOR data.

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Electron nuclear double resonance and electron paramagnetic resonance study on the structure of the NO-ligated heme alpha 3 in cytochrome c oxidase.

Cited by 48 publications

References 37 publications

Electron-nuclear coupling in nitrosyl heme proteins and in nitrosyl ferrous and oxy cobaltous tetraphenylporphyrin complexes

Electron-nuclear coupling in nitrosyl heme proteins and in nitrosyl ferrous and oxy cobaltous tetraphenylporphyrin complexes

Characterization of Bimodal Coordination Structure in Nitrosyl Heme Complexes through Hyperfine Couplings with Pyrrole and Protein Nitrogens

Revisiting the nitrosyl complex of myoglobin by high-field pulse EPR spectroscopy and quantum mechanical calculations

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