bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper‐cobalt superoxide dismutase: A re‐examination of the 1H NMR spectrum through a novel selectively deuteriated derivative
Authors: Bertini Ivano , Piccioli Mario , Scozzafava Andrea , Viezzoli Maria Silvia 
Published: May 2005

AbstractThrough 1D and 2D NOESY experiments, samples of copper‐cobalt superoxide dismutase in which the histidines had been completely deuteriated except for the β‐CH2 protons were investigated. In this way a simplified spectrum was obtained which allowed the detection of the His NHs of the cobalt domain and their assignment through the kinetics of the proton‐deuterium exchange. Further, the β‐CH2 protons of Asp 83 were stereospecifically assigned through T1 measurements. Some backbone protons were also assigned.
NMR relaxometric studies of water accessibility to haem cavity in horse heart and sperm whale myoglobin
Authors: Aime Silvio , Ascenzi Paolo , Fasano Mauro , Paoletti Silvia 
Published: May 2005

AbstractThe measurement of longitudinal relaxation rates of water protons in solutions containing horse heart and sperm whale metmyoglobins at various pH values and temperatures shows that the two species differ essentially in the exchange lifetime, τM, of the water molecule in the haem cavity. The 1/T1 nuclear magnetic relaxation dispersion dispersion profiles support this view whereas 17O NMR spectroscopy shows that the exchange mechanism involves the whole water molecule. The lack of any 1H/2H isotope effect on the exchange rate suggests that the displacement of the coordinated water molecule from Fe(III) is not the rate‐determining step in the overall exchange process. In contrast to the parent species, no difference is detectable from the relaxometric investigations on the corresponding fluorometmyoglobin derivatives.
Establishment of two distinct protein domains in blue crab Callinectes sapidus metallothionein‐I through heteronuclear (1H113Cd) and homonuclear 1H1H) correlation NMR experiments
Authors: Narula Surinder S. , Armitage Ian M. , Brouwer Marius , Enghild Jan J. 
Published: May 2005

AbstractMetallothionein is a cysteine‐rich metal‐binding protein whose biosynthesis is closely regulated by the level of exposure of an organism to zinc, copper, cadmium, etc., metal salts. The metallothionein from the crab Callinectes sapidus is known to bind six divalent metal ions. The 113Cd NMR spectrum of the 113Cdsubstituted protein shows six distinct 113Cd resonances spanning a chemical shift range of 620–665 ppm, indicating the presence of six distinct tetrahedrally coordinated divalent metal ion binding sites. Heteronuclear 1H113Cd correlation experiments revealed all the metal‐to‐cysteine connectivities present in this protein and the 2X(2113Cd)‐;filtered COSY experiment revealed that six cysteines are involved in the ligation of two Cd2+ ions. Additionally, following the complete sequential resonance assignment of the 1H NMR data, the two separate Cd3Cys9 metal binding clusters can be shown to reside in two distinct protein domains.
113Cd NMR spectra of human serum transferrin
Authors: Kiang William , Sadler Peter J. , Reid David G. 
Published: May 2005

AbstractThe binding of Cd2+ to human serum transferrin (80 kDa) was studied by 113Cd NMR spectroscopy. At pH 7 in the presence of hydrogen‐carbonate as synergistic anion, two resonances of similar intensity at 38.1 and 43.6 ppm were observed, consistent with Cd2+ binding to oxygen ligands and one nitrogen ligand in the specific metal‐binding clefts of the N‐ and C‐lobes of the protein.
NMR study of haem exchange reaction of native myoglobin and haemoglobin
Authors: Ishimori Koichiro , Morishima Isao 
Published: May 2005

AbstractA proton NMR study of the haem exchange reactions of native myoglobin and haemoglobin with the various haems revealed that the haem displacement reaction occurs in native haemoproteins as has been detected in the reconstituted haemoproteins. In the presence of an excess amount of the modified haem, protohaem was excluded from a native haemoprotein to yield a reconstituted haemoprotein containing the modified haem, suggesting that the conformational fluctuations in native haemoprotein are large enough to dissociate its haem from the haem crevice. Although the haemoglobin subunits and myoglobin exhibit very similar three‐dimensional structures as revealed by x‐ray diffraction studies, the rates of the haem exchange reactions in myoglobin were larger than those in the haemoglobin β‐subunit. Such differences in the dynamic properties suggest that these haemoproteins have different interactions between the haem and amino acid residues inside the haem pocket.
Determination of long‐range 13C, 1H coupling constants of macrolide antibiotics by 2D J—δ selective INEPT experiments
Authors: Ladam Patrick , Gharbi‐Benarous Josyane , Piotto Martial , Delaforge Marcel , Girault Jean Pierre 
Published: May 2005

Abstract2D J—δ selective INEPT experiments were used to measure long‐range 13C,1H coupling constants for the macrolide antibiotics roxithromycin, erythromycin and their metabolites, RU 39001 and erythralosamine, respectively. The 2D J—δ selective INEPT experiment was performed using selective excitation by a DANTE pulse train. In some cases, to avoid truncation problems in the t1 domain, treatment of the data using a linear prediction method was adopted. Dihedral angles for the glycosidic bonds and the erythronolid unit were deduced from a Karplus‐type equation for conformational study. The apparent equilibrium between different conformers is discussed by comparison of experimental results and theoretical calculations by molecular dynamics.
Long‐range proton spin‐spin coupling in rigid cyclic structures by 2D NMR/‘through‐space coupling’
Authors: Schröder Harald , Haslinger Ernst 
Published: May 2005

AbstractIn H,H COSY spectra of rigid cyclic terpenes, many long‐range couplings can be observed. The coupled nuclei are connected either by a zig‐zag coupling path or they are close in space. The latter are called ‘through‐space’ coupling. A certain stereospecific relationship between the coupling partners is necessary. This phenomenon is in accordance with the theoretical explanations.
Synthesis of 13C, 15N‐enriched α‐dicarbonyl model adducts to determine the utility of 13c and 15N NMR for studying mechanism‐based inactivation of cytochromes P‐450 by substituted dichloroacetamides
Authors: Weiner Scott J. , Holl Susan M. , Covey Douglas F. 
Published: May 2005

AbstractTo determine the feasibility of using NMR to study the inactivation of cytochromes P‐450 by dichloroacetamide‐containing mechanism‐based inactivators, 13C, 15N‐enriched compounds were synthesized, modeling adducts between the nucleophilic side‐chains of cysteine, lysine, serine (threonine) and tyrosine and the α‐aminooxoacyl chloride that presumably results from enzymatic conversion of a dichloroacetamide‐containing inhibitor. 13C chemical shifts of the carbonyls attached to the nucleophiles easily distinguish the model cysteine adduct (δ 192.3) from the other adducts (δ 159.6–161.8). Although the other adducts cannot be distinguished at this carbon, the carbonyl attached to the 15N two bonds away can distinguish the lysine mimic (δ 161.2 or 161.3) from the serine (threonine) and tyrosine mimics (δ 156.1–158.1). These assignments were made by comparing 15N/13C J values and were confirmed by solid‐state rotational echo double resonance (REDOR) studies. Finally, aminooxo‐15N chemical shifts three bonds removed from the nucleophile can distinguish adducts formed to lysine (δ 108.3), cysteine (δ 104.8) and oxygen‐containing side‐chains (δ 112.8–113.9).
Structure of a feruloylated arabinoxylan tetrasaccharide that contains the β‐D‐Xylp‐(1 → 2)‐α‐L‐Araf element by 1H and 13C NMR spectrocopy
Authors: Himmelsbach David S. , Hartley Roy D. , Borneman William S. , Poppe Leszek , van Halbeek Herman 
Published: May 2005

AbstractThe determination of the structure of {[5‐O‐(E)‐feruloyl] [O‐β‐D ‐xylopyranosyl‐(1 → 2)]‐O‐α‐L arabinofuranosyl‐(1 → 3)}‐O‐β‐D‐xylopyranosyl‐(1 → 4)‐D‐xylopyranose, a compound isolated from the cell walls of Gramineae, is presented. Use is made of 1D HOHAHA and 2D 1H, 13C 1H‐detected HMQC to assign the 1H and 13C NMR spectra of the individual residues. The 2D 1H, 13C 1H‐detected HMBC and 1H, 1H ROESY, in comparison with 1H, 1H COSY, experiments are used to establish the inter‐residue linkages. This is the first report of a feruloylated arabinoxylan that contains the β‐D‐Xylp‐(1 rarr; 2)‐α‐L‐Araf element.
Lithium‐7 and lithium‐6 NMR studies of solid complexes of lithium tetrahydroborate
Authors: Espidel Joussef E. , Harris Robin K. , Wade Kenneth 
Published: May 2005

AbstractLithium‐7 and lithium‐6 spectra were obtained for four solid air‐sensitive complexes of LiBH4 under both magic angle spinning (MAS) and static conditions. The MAS experiments were carried out using a specially designed rotor insert to prevent degradation of the sample. The spectra yield semi‐quantitative information about the magnitude of the quadrupolar coupling constants, but some structure in the static spectra cannot be fully explained. Chemical shift variations are, as expected, modest. Only a single MAS centreband is seen in each case, suggesting that there is only one lithium atom in the asymmetric unit.
Complete 13C 1H chemical shift assignments for trifluoromethyl‐substituted naphthylidineanilines: Remote polar effects on the naphthyl π electron distribution
Authors: Fernandez‐G. Juan M. , Enriquez Raul G. , Reynolds William F. , Yu Margaret 
Published: May 2005

Abstract13C and 1H chemical shifts are assigned, using 2D methods, for naphthylidineaniline derivatives with CF3 groups substituted in the phenyl group. The 13C chemical shifts for the naphthalene rings are interpreted in terms of remote π polarization effects.
Magnitudes and relative sign of J(119Sn,13C) and J(119Sn,H) coupling constants in some vinyltin(IV) compounds obtained by 2D NMR spectroscopy
Authors: Lyčka Antonín , Tkáč Ivan , Holeček Jaroslav , Pejchal Vladimír 
Published: May 2005

AbstractTwo‐dimensional H,C‐COSY spectra of some vinyltin(IV) compounds were measured. The relative signs of nJ(119Sn, 13C) and (n+1)J(119Sn, 1H) coupling constants were determined after analysis of the orientation of appropriate 119/117Sn satellites in H,C‐COSY spectra.
Structure elucidation and proton and carbon‐13 assignment of a pentasaccharide glycoside from Agave americana
Authors: Pant Geeta , Purohit Mahesh C. , Morris Gareth A. , Halstead Adam G. W. , Thompson Robert I. G. 
Published: May 2005

AbstractA glycoside extracted from the rhizomes of Agave americana was identified as 3‐O‐[{{β‐D‐xylosyl(1 → 3)}{β‐D‐xylosyl(1 → 3) ‐ β ‐ D ‐ glucopyranosyl(1 → 2)} ‐ β ‐ D ‐ glucopyranosyl(1 → 4)} ‐ β ‐ D ‐ galactopyranosyl] ‐ (25R) ‐ 5α ‐ spirostan‐3β‐ol by concerted use of proton and carbon‐13 2D NMR methods. Complete assignments for the sugar resonances were obtained with standard methods, but the presence of chemical shift degeneracies prevented an unequivocal determination of two of the glycosidic linkage points by the HMBC experiment. Further two‐dimensional experiments failed to resolve the ambiguity, but a clear identification of the linkages was obtained using a selective reverse INEPT experiment with homonuclear double resonance.
NMR study of the solid‐state rearrangement of 3‐amino‐1‐ and ‐2‐(chloroacetyl)pyrazole to 3‐(chloroacetamido)pyrazole
Authors: Clarke David , Mares Richard W. , McNab Hamish , Riddell Frank G. 
Published: May 2005

AbstractReaction of 3‐aminopyrazole (1) with chloroacetyl chloride gives a mixture of 3‐amino‐1‐ and ‐2‐(chloroacetyl)pyrazole (2 and 3), both of which rearrange in the solid‐state to 3‐(chloroacetamido)pyrazole (4) over a period of a few days. The course of the rearrangements was monitored directly by CP/MAS NMR and indirectly by 1H NMR spectroscopy; the results suggest that the mechanism involves 3 → 2 → 4.
Quantitative treatment of the rotational dynamics of flexible‐chain molecules. 13C NMR relaxation study of hydrocarbon chains attached to the fluorene anchor
Authors: Pissas D. , Dais Photis , Mikros E. 
Published: May 2005

Abstract13C spin‐lattice relaxation times (T1) and nuclear Overhauser enhancements (NOEs) were measured for individual carbons in flexible‐chain molecules consisting of a hydrocarbon chain attached to fluorene moiety at position 3 through an ester bond. Quantitative treatment of the relaxation data of the ring carbons revealed an anisotropic motion for all the molecules studied. The relaxation times of the chain carbons were analysed in terms of a correlation function describing multiple internal rotations about successive CC bonds. The results (rotational diffusion constants) were used to discuss features of the chain mobility as a function of chain length and chain unsaturation. The assumptions involved in the quantitative treatment were examined and the values were compared with those of n‐alkanes and lipid bilayers.
Multinuclear magnetic resonance study of some mesoionic 1,3‐diphenyltetrazoles with various exocyclic groups
Authors: Bocian Wojciech , Jaźwiński Jaroslaw , Koźmiński Wiktor , Stefaniak Lech , Webb Graham A. 
Published: May 2005

Abstract1H, 13C, 14N and 15N NMR methods were applied to the study of some Type A mesoionic 1,3‐diphenyltetrazoles with various exocyclic groups. The ring structures of these tetrazoles are confirmed by the nitrogen NMR data. The shielding of N‐4 increases consecutively by amounts of ca 10 ppm as the bonded exocyclic atom changes from S to C to O.
Nuclear quadrupolar coupling constants in the cyanoborohydride ion: T1 measurements and ab initio molecular orbital calculations
Authors: Penner Glenn H. , Custodio Angela R. 
Published: May 2005

AbstractThe 11B and 2H spin–lattice relaxation times, T1, were measured for sodium cyanoborohydride (BH3CN−) and sodium cyanoborodeuteride (BD3CN−) in methanol–ethylene glycol solution as a function of temperature. Both 11B and 2H T1 minima were observed, yielding 11B and 2H nuclear quadrupolar coupling constants, χ, of 766 and 104 kHz, respectively. Measurement of the 14N T1 at 300 K gave a χ(14N) value of 2.8 MHz. Electric field gradients were calculated using ab initio molecular orbital theory, in order to obtain theoretical 11B, 14N and 2H χ values. The values of 847 kHz, −3.25 MHz and 141 kHz for 11B, 14N and 2H, respectively, are larger than those found in solution.
Selective restricted phenyl rotation in an η3‐Ph2CCHCHPh allyl sparteine complex of Pd(II). Variable‐temperature 13C and multinuclear exchange spectroscopy
Authors: Pregosin Paul S. , Rüegger Heinz 
Published: May 2005

AbstractVariable‐temperature studies in addition to 2D exchange and NOE measurements on the chiral allyl complex [Pd(η3‐Ph2CCHCHPh){(−)‐sparteine}] [PF6] have revealed that there is restricted rotation about the ipso‐Callyl‐C bonds for the three Ph groups of the η3‐Ph2CCHCHPh ligand, with that for the anti Ph group having a much higher activation energy. Possible consequences for the reaction chemistry of 1,1‐diphenylallyl complexes due to the close proximity of this anti Ph to the chiral bidentate nitrogen ligand are discussed. Detailed 13C and 1H assignments, based on NOESY, TOCSY and C,H correlation measurements, are given.
Will the real β‐pinene please stand up
Authors: Smith William B. 
Published: May 2005

AbstractIn the past year, two complete analyses of the proton NMR spectrum of β‐pinene have appeared from different laboratories. The assignments of the chemical shifts to the protons on carbon‐3 were consistent in both studies although there was disagreement in the values assigned to the coupling constants associated with these protons. A molecular modeling study shows β‐pinene to exist in a single conformation. The proton spectrum has been re‐examined with the aid of the Ag(fod)–Yb(fod)3 reagent, and the coupling constants redetermined. The results are consistent with the modeling results and confirm that the existing assignments for the C‐3 protons should be reversed.
High‐field NMR studies on neo‐clerodane diterpenoids from Mexican Salvia species
Authors: Cárdenas J. , Esquivel B. , Rodríguez‐Hahn L. , Jankowski K. , Van Calsteren M. R. 
Published: May 2005

AbstractHigh‐field 2D NMR studies were performed on nine neo‐clerodane diterpenoids. Unambiguous assignments of the 13C signals and proton chemical shifts were achieved which led to the revision of some previous assignments.
Regioselectivity studies by selective detection of long‐range heteronuclear couplings from the SDEPT‐1D method
Authors: Parella Teodor , Sánchez‐Ferrando Francisco , Virgili Albert 
Published: May 2005

AbstractSome regiosomers formed by palladium(0)‐catalysed allylation of several ambident heterocyclic nucleophiles, among others, were easily distinguished in very short spectrometer times by selective polarization transfer via DEPT from well resolved protons to long‐range coupled carbons using the SDEPT‐1D experiment. This pulse sequence was also analysed in terms of the product operator formalism. These structural elucidations can provide useful information about the regioselectivity in these reactions.
Multinuclear NMR study of protonation in some indolizine systems
Authors: Wiench Jerzy W. , Stefaniak Lech , Webb Graham A. 
Published: May 2005

Abstract1H, 13C and 15N NMR data are presented for seven indolizine derivatives in solutions of dimethyl sulphoxide and trifluoroacetic acid (TFA). The TFA solutions contain species protonated at position N‐1 in all cases. The most definitive evidence for the site of protonation is provided by the 15N results.
Extensive high‐resolution reverse 2D NMR analysis for the structural elucidation of procyanidin oligomers
Authors: Balas Laurence , Vercauteren Joseph 
Published: May 2005

AbstractThe structures of the procyanidin dimers catechin‐(4α–8)‐catechin and catechin‐(4α–6)‐catechin were proved by spectroscopic means. To distinguish between the two possible interflavanoid linkages, it is necessary to assign all the quaternary aromatic carbon signals. How these assignments can be made through two‐dimensional NMR spectroscopy is described.
Generalized relationship for calculation of nuclear spin—spin coupling constants between directly bonded carbon and hydrogen atoms
Authors: Zhan Chang‐Guo , Hu Zhen‐Min 
Published: May 2005

AbstractA generalized relationship to describe bond coupling constants is introduced. This expression includes the contributions for hybrid orbitals and the net atomic charges. The resulting expression provides an excellent description of directly bonded CH coupling constants. This equation is suitable both for hydrocarbons and for molecules with I+ and I− substituents.
Analysis of the 13C and 1H spectra of mixtures of benzylidene derivatives
Authors: Bradley J. C. , Williams A. J. 
Published: May 2005

AbstractThe 1H and 13C NMR spectra of methyl (E)‐2,3,‐diphenylprop‐2‐enoate and methyl (E)‐2‐(2‐phenylethenyl) benzoate resulting from the electrocyclic ring opening of benzocyclobutenone starting materials have been assigned. A combination of direct detection 2D NMR techniques, COSY, HETCOR and FLOCK, provided the assignments of the 1H and 13C resonances.
Proton resonance spectra and substituent‐induced chemical shifts of 3‐halocamphors
Authors: Kaiser C. R. , Rittner R. , Basso E. A. 
Published: May 2005

AbstractComplete signal assignments of high‐field 1H NMR spectra for 3‐halosubstituted camphors (endo and exo) are presented, allowing a refinement of a previous analysis for the chloro (endo and exo) and bromo (endo) derivatives. In addition, still unpublished data for the dichloro and exo‐fluoro derivatives and for three new compounds (endo‐fluoro, endo‐ and exo‐iodo), in addition to a revised assignment of the camphor parent molecule, are reported. The precise substituent‐induced chemical shifts (SCS) obtained for these difunctional systems are examined on the basis of well known transmission mechanisms aided by correlations with steric and electronic parameters, and taking into account SCS data from monohaloalkanes and the calculated molecular geometry data (using the AM1 method).
NMR studies of the luteinizing hormone‐releasing hormone (LH‐RH) decapeptide in DMSO solution
Authors: Calzolai Luigi , Gaggelli Elena , Valensin Gianni , Maccotta Antonella 
Published: May 2005

AbstractThe structure of LH‐RH in DMSO solution was studied using 2D NMR experiments at 600 MHz. The 13C NMR spectrum was completely assigned by the combined use of 1H‐detected heteronuclear multiple‐quantum coherence and 1H‐detected multiple‐bond heteronuclear multiple‐quantum coherence. Measured 1J(CH) values were used to obtain the possible sets of Φ and Ψ dihedral angles. These features, together with some relevant dipolar interactions observed in the ROESY spectrum, were interpreted to provide evidence of some degree of intramolecular structuring.
15N NMR chemical shifts for cyanamide, phenylcyanamide and a series of phenyl‐substituted derivatives
Authors: Buchanan G. W. , Crutchley R. J. 
Published: May 2005

Abstract15N NMR chemical shifts are reported for cyanamide, phenylcyanamide and nine substituted phenylcyanamide derivatives. Results are discussed in terms of the degree of the π interaction between the cyanamide moiety and the aromatic ring and the stereoelectronic influence of the substituents.
13C NMR of some iodinated methoxy‐amphetamines
Authors: Dawson Brian A. , Black D. B. , Sy W.‐W. , Graham K. 
Published: May 2005

Abstract13C NMR chemical shift assignments for 14 iodinated methoxyamphetamines were measured and interpreted. Chemical shift assignments for these compounds have not been reported previously. Data are based on a number of one‐ and two‐dimensional experiments performed at 9.4 T.
Hydroacridines. XIV—carbon‐13 NMR spectra of three perhydroacridine stereoisomers
Authors: Potmischil Francisc , Kalchhauser Hermann 
Published: May 2005

AbstractThe 13C NMR chemical shifts of (4aα,8aα, 9aβ, 10aα)‐, (4aα,8aα,9aα, 10aβ)‐ and (4aα,8aβ,9aα, 10aβ)‐tetradecahydroacridine were measured and fully assigned on the basis of APT, 13C, 1H shift correlation and 2D‐INADEQUATE spectra.
13C, 1H long‐range coupling constants in configuration assignment of some trisubstituted alkenes
Authors: Fischer Peter , Schweizer Eberhard , Langner Jörg , Schmidt Ulrich 
Published: May 2005

AbstractChemical shifts and long‐range 13C, 1H coupling constants to the two carbonyl C atoms were determined for a series of ethyl 2‐acyloxy‐2‐alkenoates. The 3J(C,H) coupling constant across the double bond is 9.5–10.1 Hz for the E‐ and 2.9–3.8 Hz for the Z‐isomer. 3J(C,H) values, therefore, may be used as a criterion for E/Z differentiation even if only one isomer is available. 13C chemical shift data, in contrast, cannot be employed for a straightforward differentiation.
Dependence of one‐bond deuterium isotope shifts in 13C NMR on CH bond lengths for substituted and unsubstituted aromatic compounds
Authors: Nakashima Yasuki , Teranishi Takashi , Suzuki Toshiya , Sone Tyo , Takahashi Kensuke 
Published: May 2005

AbstractOne‐bond deuterium‐induced isotope shifts of 13C NMR (1Δ) for 106 sp2‐hybridized carbons are discussed in terms of CH bond lengths. 1Δ correlates linearly with the related CH bond length calculated by the MNDO MO method by the equation 1Δ(ppb)=8350 rCH (Å) – 8824.