NMR Hyperfine Research Articles

Disorder and double-exchange spin dynamics inLa0.7Sr0.3MnO3andLa0.7Sr0.3CoO3from NMR hyperfine couplings

Disorder and double-exchange spin dynamics in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">La</mml:mi><mml:mn>0.7</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">Sr</mml:mi><mml:mn>0.3</mml:mn></mml:msub><mml:mi mathvariant="normal">Mn</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">La</mml:mi><mml:mn>0.7</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">Sr</mml:mi><mml:mn>0.3</mml:mn></mml:msub><mml:mi mathvariant="normal">Co</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>from NMR hyperfine couplings

A justification for using NMR model‐free methods when investigating the solution structures of rhombic paramagnetic lanthanide complexes

The detailed analysis of the 1H NMR hyperfine shifts according to the model-free methods shows that the semi-rigid monometallic complexes [Ln(L)(NO3)3] (Ln = Eu-Yb) are isostructural in solution. The associated separation of contact and pseudo-contact contributions to the hyperfine NMR shifts in each rhombic lanthanide complex at room temperature provides paramagnetic susceptibility tensors whose principal magnetic axes match the expected symmetry requirements. Moreover, both axial (Delta chi(ax)) and rhombic (Delta chi(rh)) paramagnetic anisotropies display satisfactory linear dependence on Bleaney's factors, a correlation predicted by the approximate high-temperature expansion of the magnetic susceptibility limited to T(-2). Consequently, the simple, and chemically attracting NMR model-free methods are not limited to axial systems, and can be safely used for the investigation of the solution structures of any lanthanide complexes. Molecular-based structural criteria for the reliable estimation of paramagnetic susceptibility tensors by NMR are discussed, together with the assignment of the labels of the crystal-field and magnetic axes within Bleaney's approach.

Suppression of Axial Methionine Fluxion in Hydrogenobacter thermophilus Gln64Asn Cytochrome c552

Proteins in the cytochrome c (cyt c) family with His-Met heme axial ligation display diverse heme electronic structures as revealed by the NMR spectra of their oxidized (paramagnetic) forms. These variations in electronic structure are thought to result primarily from differences in heme axial Met orientation among cyt c species. The factors determining Met orientation in cyts c, however, remain poorly understood. An additional layer of complexity was revealed with the recent finding that the axial Met in Hydrogenobacter thermophilus cytochrome c(552) (Ht cyt c(552)) is fluxional, sampling two conformations rapidly on the NMR time scale, resulting in an unusual compressed range of heme substituent hyperfine shifts [Zhong, L., Wen, X., Rabinowitz, T. M., Russell, B. S., Karan, E. F., and Bren, K. L. (2004) Proc.Natl. Acad. Sci. U.S.A. 101, 8637-8642]. In this work, the (1)H NMR hyperfine shift pattern of Ht cyt c(552) is drastically altered by making the conservative heme pocket mutation Gln64Asn. The mutant (Ht Q64N) displays a pattern of heme hyperfine shifts with a remarkable resemblance to that of structurally homologous Pseudomonas aeruginosa cyt c(551), which has Asn at position 64 and a single heme axial Met conformation. NMR analysis reveals that Asn64 in Ht Q64N is positioned to interact with the axial Met61, whereas the Gln64 in wild-type Ht cyt c(552) is not. It also is found that the heme axial Met is not fluxional in Ht Q64N and has an orientation similar to that in P. aeruginosa cyt c(551). These results indicate that peripheral interactions with the axial Met play an important role in determining axial Met orientation and heme electronic structure in cyts c.

Backbone and side-chain heteronuclear resonance assignments and hyperfine NMR shifts in horse cytochrome c.

The [H26N, H33N] mutant of horse heart cytochrome c was expressed in E. coli during growth on isotopically enriched minimal media. Complete resonance assignments of both the diamagnetic reduced (spin zero) and paramagnetic oxidized (spin (1/2)) states of the protein were obtained using standard triple resonance and total correlation spectroscopy using the previously determined (1)H chemical shifts of the wild-type protein as a guide. The correspondence of chemical shifts between the wild type and the mutant protein is excellent, indicating that they have nearly identical structures. The expanded library of chemical shifts for both redox states in both proteins allowed the refinement of the electron spin g-tensor of the oxidized states. The g-tensors of the oxidized states of the wild-type and [H26N, H33N] mutant proteins are closely similar, indicating that the subtle details of the ligand fields are nearly identical. The refined g-tensors were then used to probe for redox-dependent structure change in the two proteins.

The solution structure of homotrimetallic lanthanide helicates investigated with novel model-free multi-centre paramagnetic NMR methodsElectronic supplementary information (ESI) available: tables of structural factors Cikl, Dikl obtained for the model complexes and for [Ln3(L1)3]9+ in solution (Table S1) and geometrical factors calculated for the structure of [Eu3(L1)3]9+ optimized in the gas phase (Table S2). Figures showing a plot of 1/Tpara1i vs.

The combination of one contact and three pseudo-contact contributions to the NMR hyperfine paramagnetic shift of each proton in the triple-stranded helicates [Ln3(L1)3]9+ (Ln = Ce–Yb except Pm, Gd) produce intractable 1H NMR spectra whose assignment is limited by the large electronic contribution to the nuclear relaxation processes. The detailed analysis of the NMR spectra for the diamagnetic complexes [Ln3(L1)3]9+ (Ln = La, Lu, Y) shows that the triple-helical structure found in the solid state is maintained in solution. Extension of the classical one-nucleus crystal-field dependent model-free method for paramagnetic D3-symmetrical homotrimetallic lanthanide complexes possessing two different metallic sites (i.e. two second-rank crystal-field parameters: B20central and B20terminal) allows (i) the complete interpretation of the paramagnetic signals for Ln = Ce–Yb and (ii) the detection of a concomitant abrupt change of the contact terms Fi and of the pseudo-contact terms Si = B20centralG1i + B20terminal(G2i + G3i) occurring near the middle of the lanthanide series. The derivation and application of a novel three-nuclei crystal-field independent method eventually demonstrates that the helicates [Ln3(L1)3]9+ adopt a single D3-symmetrical structure along the complete lanthanide series in solution, which ascribes the discontinuity observed for Si to a concomitant decrease of the two crystal-field parameters. Comparison with structural models is limited by the extreme sensitivity of the structural factors Cikl and Dikl to minor geometrical variations affecting the wrapping of the ligand strands, but calculations of the geometrical factors Gmi (m = 1–3) for [Ln3(L1)3]9+ in solution confirm the formation of a regular triple-helical structure. Generalization of this novel three-nuclei method for addressing the solution structure of rhombic lanthanide complexes is discussed.

Analysis of paramagnetic NMR spectra of triple-helical lanthanide complexes with 2,6-dipicolinic acid revisited: a new assignment of structural changes and crystal-field effects 25 years later.

Variable-temperature (1)H and (13)C NMR measurements of the D(3)-symmetrical triple-helical complexes [Ln(L1-2H)(3)](3)(-) (L1 = pyridine-2,6-dicarboxylic acid; Ln = La-Lu) show evidence of dynamic intermolecular ligand-exchange processes whose activation energies depend on the size of the metal ion. At 298 K, the use of diastereotopic probes in [Ln(L3-2H)(3)](3)(-) (L3 = 4-ethyl-pyridine-2,6-dicarboxylic acid) shows that fast intramolecular P <==> M interconversion between the helical enantiomers occurs on the NMR time scale. Detailed analyses of the paramagnetic NMR hyperfine shifts according to crystal-field independent techniques demonstrate the existence of two different helical structures, one for large lanthanides (Ln = La-Eu) and one for small lanthanides (Ln = Tb-Lu), in complete contrast with the isostructurality proposed 25 years ago. A careful reconsideration of the original crystal-field-dependent analysis shows that an abrupt variation of the axial crystal-field parameter A(0)2<r (2)> parallels the structural change leading to some accidental compensation effects that prevent the detection of structural variations according to the classical one-nucleus method. Crystal structures in the solid state and density functional theory calculations in the gas phase provide structural models that rationalize the paramagnetic NMR data. A regular triple-helical structure is found for small lanthanides (Ln = Tb-Lu) in which the terdentate chelating ligands are rigidly tricoordinated to the metals. A flexible and distorted structure is evidenced for Ln = La-Eu in which the central pyridine rings interact poorly with the metal ion. The origin of the simultaneous variation of structural parameters and crystal-field and hyperfine constants near the middle of the lanthanide series is discussed together with the use of crystal-field-independent techniques for the interpretation of paramagnetic NMR spectra in axial lanthanide complexes.

Spin Polarization in Infinite Zigzag Chains of [Rh 2 (HNCOCH 3 ) 4 Cl] n

A temperature dependence of 13 C CPMAS NMR was measured for revealing the local electron spin structure in [Rh 2 (acam) 4 Cl] n (Hacam=acetamide). Observed two sharp peaks were assigned to carbons of crystallographycally nonequivalent CH 3 groups and a broad one to C in the C=O group. A large high-field shift of -125 ppm was observed in C (C=0), indicating a negative spin polarization on this carbon. From the temperature dependence of Fermi contact shifts, the hyperfine coupling constant of each carbon was determined. By considering hyperfine coupling constants, it is found that a marked amount of electron spins are distributed on C (C=O) with the negative polarization, and a small positive spin exists even on the terminal carbons in methyl groups. 1 H MAS NMR spectra can be explained by the superposition of different shift lines, implying that spin polarization is also generated on hydrogen atoms. Rhodium complex Acetamidato complex Dinuclear complex Electron spin polarization 13 C CPMAS NMR Hyperfine coupling constant

Synthesis and NMR studies of new DOTP-like lanthanide(III) complexes containing a hydrophobic substituent on one phosphonate side arm.

Three derivatives of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonic acid) (DOTP) containing a hydrophobic substituent on one side chain were prepared and their lanthanide complexes examined by NMR. The new ligands include 1-(1-octyl-methyl-phosphonic acid)-4,7,10-tris(methylene phosphonic acid)-1,4,7,10-tetraazacyclododecane (C(8)-DOTP), 1-(1-undecyl-methyl-phosphonic acid)-4,7,10-tris(methylene phosphonic acid)-1,4,7,10-tetraazacyclododecane (C(11)-DOTP), and 1-(1-4-nitro-phenyl-methyl-phosphonic acid)-4,7,10-tris(methylene phosphonic acid)-1,4,7,10-tetraazacyclododecane (NO(2)-Ph-DOTP). (1)H NMR spectra of the ytterbium(III) complexes were assigned by using a combination of COSY spectroscopy and a fitting procedure that matches experimental NMR hyperfine shifts with those estimated from a MMX-derived structure. The analysis showed that a single isomer is present in solution and that the bulky hydrophobic substituent occupies the less sterically demanding H(6) equatorial position in the YbL(5)(-) complexes. Although the YbL(5)(-) complexes have lower symmetry due to the added substituent, the average (1)H hyperfine shifts are 5-10% larger in these complexes compared to YbDOTP(5)(-). This was magnified further in the hyperfine (23)Na NMR shifts of ion-paired sodium ions where the extracellular Na(+) signal in perfused rat hearts displayed a 28% larger hyperfine shift in the presence of Tm(C(11)-DOTP)(5)(-) than with an equivalent amount of TmDOTP(5)(-).

(2)H MAS NMR studies of the manganese dioxide tunnel structures and hydroxides used as cathode materials in primary batteries.

Variable-temperature (2)H MAS NMR spectroscopy was used to investigate the local environments and mobility of deuterons in the manganese dioxide tunnel structures. Five systems were investigated: electrolytic manganese dioxide (EMD), the model compounds groutite and manganite, and deuterium intercalated ramsdellite and pyrolusite. Ruetschi deuterons, located in the cation vacancy sites in EMD, were detected by NMR and give rise to a resonance at 150 ppm at room temperature. These deuterons are rigid on the (2)H MAS NMR time scale (i.e., the correlation time for motion, tau(c), is >10(-3) s) at room temperature, but start to become mobile above 150 degrees C. No Coleman protons (in the so-called 1 x 1 and 1 x 2 tunnels in EMD) were observed. Much larger (2)H NMR hyperfine shifts of approximately 300 and approximately 415 ppm were observed for the deuterons in the tunnel structures of manganite and groutite, which could be explained by considering the different bonding arrangements for deuterons in the 1 x 1 and 1 x 2 tunnels. The smaller shift of the EMD deuterons was primarily ascribed to the smaller number of manganese ions in the deuterium local coordination sphere. Experiments performed as a function of intercalation level for ramsdellite suggest that the 1 x 1 tunnels are more readily intercalated in highly defective structures. The almost identical shifts seen as a function of intercalation level for deuterons in both 1 x 1 and 1 x 2 tunnels are consistent with the localization of the e(g) electrons near the intercalated deuterium atoms. A Curie-Weiss-like temperature dependence for the hyperfine shifts of EMD and groutite was observed with temperature, but very little change in the shift of the manganite deuterons was observed, consistent with the strong antiferromagnetic correlations that exist above the Néel temperature for this compound. These different temperature dependences could be used to identify manganite-like domains within the sample of groutite, which could not be detected by X-ray diffraction.

Structural Information through NMR Hyperfine Shifts in Blue Copper Proteins

The oxidized blue copper proteins azurin and stellacyanin have been investigated through 1H NMR at 800 MHz and the results compared with those for plastocyanin (Bertini, I.; Ciurli, S.; Dikiy, A.; Gasanov, R.; Luchinat, C.; Martini, G.; Safarov, N. J. Am. Chem. Soc. 1999, 121, 2037). By exploiting saturation transfer between the oxidized and the reduced forms, all the hyperfine shifted signals can be assigned, including the β-CH2 protons of the coordinated cysteines, which are so broad not to be detected under direct observation. Both hyperfine shifts and line widths of the latter signals differ dramatically from one protein to another: average hyperfine shifts of about 850, 600, and 400 ppm and average line widths of 1.2, 0.45, and 0.25 MHz are observed for azurin, plastocyanin, and stellacyanin, in that order. The observation of a nuclear line width of 1.2 MHz is unprecedented in high-resolution NMR in solution. These data are interpreted as a measure of the out-of-plane displacement of the copper ion,...

Combination of crystal-field dependent and independent paramagnetic NMR hyperfine shift analysis methods for investigating the solution structures of inert self-assembled heterodimetallic d–f supramolecular complexes †

Tables of molecular peaks obtained by ESI-MS, longitudinal and transverse relaxation times, axial paramagnetic anisotropies and axial co-ordinates for (HHH)-[LnCo IIIL 3] 6+ in acetonitrile; tables of least-squares planes and structural data for 6 and 7; tables of geometric factors R ik and intercepts F″ i − F kR ik for (HHH)-[LnCo II(L) 3] 5+ in acetonitrile; figures showing packing in 7, linear plots of relaxation rates versus the square of magnetic fields for (HHH)-[LnCo IIL 3] 6+ and a plot of Δ ij/<S z> j vs. Δ kj/<S z> j for H 12–H 13 in (HHH)-[LnCo IIL 3] 5+ in acetonitrile DOC (512K) Crystal structure data TXT (69K)

Determination of 13C NMR isotropic Knight shift and deviation from BCS relation in A3C60 superconductors.

We determined the isotropic {sup 13}C NMR hyperfine coupling constant as {ital a}{sub iso}/2{pi}=0.69{plus_minus}0.06 MHz for the C{sub 60}{sup 3{minus}} ion near room temperature (RT). On this basis, the spin susceptibility at RT, {chi}{sub {ital s}}(RT), was estimated in various alkali-metal doped C{sub 60} compounds {ital A}{sub 3}C{sub 60}, which is approximately proportional to the lattice constant {ital a}{sub 0}; we found {ital d}{chi}{sub {ital s}}/{ital da}{sub 0}=(0.61{plus_minus}0.06){times}10{sup {minus}3} (emu/moleC{sub 60})/A . The correlation between the superconducting transition temperature {ital T}{sub {ital c}} and {chi}{sub {ital s}}(RT) was determined. It was found that {ital T}{sub {ital c}} of Na{sub 2}RbC{sub 60}, Na{sub 2}KC{sub 60}, Li{sub 2}CsC{sub 60}, and ammoniated {ital A}{sub 3}C{sub 60} is significantly lower than that expected from the BCS relation based on {chi}{sub {ital s}}(RT). {copyright} {ital 1996 The American Physical Society.}

Influence of Meso Substituents on Electronic States of (Oxoferryl)porphyrin pi-Cation Radicals.

A series of (oxoferryl)porphyrin pi-cation radicals generated from porphyrins substituted at the meso positions with highly electron-withdrawing aryl groups has been characterized: tetrakis-5,10,15,20-(2,6-dichlorophenyl)-, 5-(2-chloro-6-nitrophenyl)-10,15,20-tris(2,6-dichlorophenyl)-, and 5-(2,6-dinitrophenyl)-10,15,20-tris(2,6-dichlorophenyl)porphyrins (porphyrins 1-3, respectively). The physical-chemical properties of the oxidized complexes of 1-3 are compared to those of two (oxoferryl)porphyrin pi-cation radical complexes substituted with electron-releasing aryl groups: tetramesitylporphyrin (TMP) and 2-iodotetramesitylporphyrin (2-iodoTMP). While all of the complexes examined show close correspondance in a number of spectroscopic parameters, some significant differences were observed. In contrast to observations for the oxidized complexes of TMP and 2-iodoTMP, the resonance Raman marker bands nu(2) and nu(11), which are indicators of symmetry state of porphyrin pi-cation radicals of 1-3, do not show the expected downfrequency shifts for oxidation to compound I analogs in a(2u) symmetry states. The upfield hyperfine NMR shifts of the pyrrole beta-proton signals of the compound I analogs of 1-3 are much larger than those for TMP and 2-iodoTMP. These data may be explained by admixture of some a(1u) character into the ground state of radical cations of 1-3, consistent with the hypothesis that electron-withdrawing meso substituents lower the energy of the a(2u) molecular orbital, favoring an a(1u) admixture.

The pH dependent spectral properties of Clostridium pasteurianum 2[Fe 4S 4] ferredoxin

The recently assigned 1H NMR hyperfine signals of Clostridium pasteurianum ferredoxin were investigated over the pH range 8–12 to monitor possible pH-dependent conformational changes of the protein. For very high pH values minor perturbations were detected in the chemical shifts of three signals assigned to β-CH 2, cysteine protons of cluster II, while cluster I was not affected at all. These chemical shift variations, which can be fitted to a single p K a ≈ 10.9, are interpreted as an effect of deprotonation of the phenolic group of Tyr-2, located reasonably close to cluster II. This hypothesis has been supported by means of other techniques such as CD and absorption spectroscopy that, on turn, are able to reveal minor pH-dependent spectral variations at high pH. Finally a UV difference experiment has provided further evidence for deprotonation of the phenolic group of Tyr-2. The possible influence of deprotonation of Tyr-2 on the redox properties of cluster II is discussed.

Magnetic resonance spectroscopy, calcium content, and anion coordination studies of bovine and goat lactoperoxidase

Bovine lactoperoxidase from two purebred strains and a commercial source as well as lactoperoxidase isolated from Alpine goat milk were examined by proton NMR spectroscopy for structural comparison of the heme site. Hyperfine shifted proton NMR spectra for both the native enzymes and cyanide complexes were equivalent for the protein obtained from the four separate sources. Activity assays (guaiacol and iodide ion oxidations) were also employed to compare the enzyme from various sources. Bovine lactoperoxidase was shown to contain 1.5 ± 0.1 calcium ions per heme unit. Lactoperoxidase complexes with nitrite ion and thiocyanate ion were characterized for comparison with the cyanide complex. The nitrite complex exhibits a proton NMR hyperfine shift pattern at ambient temperature consistent with a low-spin ferric formulation. Interaction of lactoperoxidase with thiocyanate ion was monitored by NMR and EPR spectroscopy. Proton NMR spectra of lactoperoxidase in the presence of excess thiocyanate ion illustrated the retention of a high-spin ferric configuration consistent with predominant binding of the physiological thiocyanate substrate at a non-heme site at room temperature. However, EPR spectroscopy at cryogenic temperatures revealed the existence of a low-spin lactoperoxidase thiocyanate complex. This result may be explained by low-affinity ambient temperature thiocyanate heme binding that is greatly enhanced at liquid helium temperature.

Proton NMR hyperfine shift pattern as a probe for ligation state in high-spin ferric hemoproteins: water binding in metmyoglobin mutants

Proton NMR hyperfine shift pattern as a probe for ligation state in high-spin ferric hemoproteins: water binding in metmyoglobin mutants

Assignment of proton hyperfine NMR resonances in met—cyano monomer hemoglobin components from glycera dibranchiata using deuterium-labelled hemes

Assignment of proton hyperfine NMR resonances in met—cyano monomer hemoglobin components from glycera dibranchiata using deuterium-labelled hemes

Identification of the altered pyrrole in the isomeric sulfmyoglobins: hyperfine shift patterns as indicators of ring saturation in ferric chlorins.

Analysis of the 1H NMR hyperfine shift patterns of isomeric sulfmyoglobins is carried out in the met-aquo and met-cyano states to determine the site of saturation in each protein. The utility of the patterns for structure elucidation is established by specific deuterium labeling of the heme methyls of the terminal base product. On the basis of the known saturation of ring B in this isomer [Chatfield, M.J., La Mar, G.N., Lecomte, J.T.J., Balch, A.L., Smith, K.M., & Langry, K.C. (1986) J. Am. Chem. Soc. 108, 7108-7110], the methyl resonance of the saturated ring is found to have strongly attenuated contact shift. Thus, the heme methyl contact shift pattern is diagnostic for the saturated pyrrole in the high-spin state. This rationale is then applied to analyze the assigned NMR spectra of the initial and terminal acid sulfmyoglobin products, revealing that the same ring B is saturated in each isomer. In contrast, the heme methyl contact shift pattern in low-spin ferric complexes reveals that the methyls both on the affected pyrrole and on the trans pyrrole are influenced similarly on sulfmyoglobin formation, precluding the use of this methyl shift pattern as a unique indicator of the site of saturation. Identification of exchangeable proximal histidine resonances for met-aquo sulfmyoglobin complexes with shifts similar to that in native myoglobin dictates inconsequential axial alterations in the sulfmyoglobins, while location of downfield meso proton resonances analogous to those of the native protein demonstrates the retention of the coordinate water in the active site of met-sulfmyoglobin.

ChemInform Abstract: MESO DEUTERIUM NMR HYPERFINE SHIFT AS A PROBE FOR DETERMINING FIVE‐ OR SIX‐COORDINATION AT HEME IRON BINDING SITE IN FERRIC HIGH‐SPIN HEMOPROTEINS

Chemischer InformationsdienstVolume 16, Issue 27 Physical Organic Chemistry ChemInform Abstract: MESO DEUTERIUM NMR HYPERFINE SHIFT AS A PROBE FOR DETERMINING FIVE- OR SIX-COORDINATION AT HEME IRON BINDING SITE IN FERRIC HIGH-SPIN HEMOPROTEINS I. MORISHIMA, I. MORISHIMASearch for more papers by this authorY. SHIRO, Y. SHIROSearch for more papers by this authorT. WAKINO, T. WAKINOSearch for more papers by this author I. MORISHIMA, I. MORISHIMASearch for more papers by this authorY. SHIRO, Y. SHIROSearch for more papers by this authorT. WAKINO, T. WAKINOSearch for more papers by this author First published: July 9, 1985 https://doi.org/10.1002/chin.198527050AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume16, Issue27July 9, 1985 RelatedInformation

Meso deuterium NMR hyperfine shift as a probe for determining five- or six-coordination at heme iron binding site in ferric high-spin hemoproteins

Meso deuterium NMR hyperfine shift as a probe for determining five- or six-coordination at heme iron binding site in ferric high-spin hemoproteins