Nuclear Magnetic Resonance Properties Research Articles

Nuclear magnetic resonance properties of gynecological tissues

Nuclear magnetic resonance (NMR) can distinguish malignant tissue from histologically negative tissue in cervix, myometrium, and ovary in a cancer-free host or a host with cancer in a different organ. In cervix and myometrium NMR can distinguish malignant from benign lesions. Cancer in the cervix elevates the NMR values in adjacent, histologically negative cervical tissue.

Preparation and vibrational spectra of tetra-n-propylammonium carbonyldichloro-organoplatinate(II) salts, and a comparison of their carbon-13 and platinum-195 nuclear magnetic resonance properties with those of organomercury compounds

Salts, [NPrn4][PtCl2R (CO)](R = Me, Et, Prn, Pri, Bun, or Ph), have been prepared from the reaction of [NPrn4]2-[Pt2Cl4(CO)2] with HgR2, but derivatives with R = But, C2H3, or C3H5 could not be obtained. Infrared and Raman spectra are reported and discussed. The 1H, 13C, and 1H-{195Pt} INDOR spectra have been investigated. The behaviours of 1J(PtC) and δ(195Pt) are discussed with reference to the 13C parameters and δ(199Hg) of the mercury compounds, [HgX(R)](X = Cl, Br, I, or R).

3‐Monosubstituted and 3,6‐Unsymmetrically disubstituted 1,2,4,5‐Tetrazines. A general method of synthesis

AbstractA stepwise procedure has been developed for the synthesis of 3,6‐unsymmetrically disubstituted‐ or 3‐monosubstituted‐1,2,4,5‐tetrazines, based upon the facile substitution either of an alkylthio group in 3,6‐bis(alkylthio)‐1,2,4,5‐tetrazines (1) and (2) by nitrogen nucleophiles, particularly by hydrazine, or of a bromo group, obtained by oxidation of a hydrazino group or by an independent synthesis, by carbon nucleophiles. The ultraviolet‐visible spectra and some nuclear magnetic resonance properties are discussed.

Fluorine-19 nuclear magnetic resonance studies of effects of ligands on trifluoroacetonylated supernatant aspartate transaminase.

The selective reaction of Cys-45 and -82, on the one hand, and Cys-390, on the other, with 3-bromo-1,1,1-trifluoropropanone allows for the probing of these regions of aspartate transaminase in the absence and in the presence of enzymatic ligands by 19F nuclear magnetic resonance (NMR). The 19F chemical shifts of the resonance lines differ for the three cysteines and so does their behavior with pH changes. The resonance signals with chemical shifts at 615 and 800 Hz upfield from trifluoroacetic acid correspond to modified cysteine-82 and -45 and have tentatively been assigned in this order. The 615-Hz resonance is affected by pH changes that fit best the influence of a single ionizing residue. On the 800-Hz line, the pH changes appear to be the influence of a minimum of two ionizing residues. The 19F resonance from modified Cys-390 is pH independent in the pH range 5-9 for the pyridoxal phosphate, pyridoxamine phosphate, and apoenzyme forms of the enzyme. Occupation of the active site by a quasi-enzyme-substrate complex, trifluoromethionine pyridoxyl phosphate, affects the 19F chemical shift of modified Cys-390, making it pH dependent with a pK value of 8.4. The 19F NMR properties of the pyridoxal form of Cys-390-modified enzyme can be used to monitor some ligand interactions with the active-center region. Addition of alpha-ketoglutarate or succinate to the ketone labeled enzyme causes a decrease in the resonance line width, and titrations show that this procedure is a good method with which to study the affinity of the enzyme for these ligands. The interpretation of the chemical shift and line-width characteristics of the 19F resonance arising from Cys-390 are most consistent with a model in which the region around this residue seems to be affected by conformational changes arising from substrate binding to the active-center subsites in productive (covalent) manner. Nonproductive complexes which possess fast ligand-protein exchange, such as those between alpha-ketoglutarate or succinate with the pyridoxal phosphate form of the enzyme, may result only in a greater degree of freedom for Cys-390.

Nuclear magnetic resonance and relaxation properties of solid SF6

Line shape and relaxation studies of the low temperature solid phase of SF6 stable below 94 K show the presence of two inequivalent lattice sites, one-quarter of the SF6 molecules being characterized by a barrier to isotropic reorientation of 1.9 and the remainder by a barrier of 2.8 kcal/mole. The chemical shift anisotropy (σ∥−σ⊥) of the S–F bond in SF6 is found to be 300±50 ppm. The sensitivity of line shape to rf field level in the cubic phase between 94 and 135 K is adequately described by the Goldman–Provotorov theory of ’’saturation narrowing’’. The activation energy for translational diffusion in this phase is 9.8 kcal/mole.

Poly(amide‐acetals) and poly(ester‐acetals) from polyol acetals of methyl 9(10)‐formylstearate: Preparation and physical characterization

AbstractCondensation polymers were prepared from the pentaerythritol acetal of methyl 9(10)‐formylstearate by reaction with diamines and with ethylene glycol. The glycerol acetal was self‐condensed to a poly(ester‐acetal) and also copolymerized with caprolactam. A novel step growth, addition polymerization was carried out with ethylene bis[9(10)‐methoxymethylenesterate] and pentaerythritol. Physical and spectral (infrared and nuclear magnetic resonance) properties of the various products were determined. In general, the long C8–C9 side chains in the polymers of the pentaerythritol acetal of methyl 9(10)‐formylstearate reduced crystallinity to such a degree that, unlike polymers from methyl azelaaldehydate pentaerythritol acetal, they were soluble in the more ordinary solvents, e.g., chloroform and tetrahydrofuran.

Paramagnetic resonance studies in ferroelectric tris-sarcosine calcium chloride

Dielectric, structural and nuclear magnetic resonance (nmr) properties of TSCC point at a ferroelectric transition of the order-disorder type, which may be triggered by the dynamics of the protons in the hydrogen bonds. From electron paramagnetic resonance (epr) experiments on TSCC: Mn2+ a relation between fine structure and the time average of the quasi spin variables has been found. Electron spin-echo (ese) measurements of the transverse relaxation time and epr line width investigations near transition temperature are consistent with an anisotropic Ising model of the relaxation type. The static rotation angle of the fine structure tensor correlates with the macroscopic order parameter. Its temperature dependence yields an effective critical exponent whose variation may be interpreted as the influence of order parameter fluctuations on the order of the phase transition.

Nuclear magnetic resonance study of ligand binding to Mn-aspartate transcarbamylase.

Aspartate transcarbamylase from Escherichia coli has been prepared with up to four of zinc ions replaced by manganese, and the effect of this substitution on the proton nuclear magnetic resonance properties of succinate bound to the catalytic site and of cytidine 5'-triphosphate bound to the regulatory site has been determined, The specific activity and allosteric properties of the Mn-substituted enzyme are essentially identical with those of the native enzyme. The longitudinal relaxation time, T1, of the succinate protons is shortened by the native enzyme and is shortened further by the Mn-substituted enzyme at both 100 and 220 MHz in D2O solutions of 0.02 M immidazole chloride (pH 7.0), 10 minus 3 M beta-mercaptoethanol, 0;2 mM ethylenediamenetetraacetic acid, and 2.5 mM carbamyl phosphate over a temperature range of 5 to 35 degrees. Under the same conditions, the transverse relaxation time, T2, of the succinate protons at 90 MHz is shortened to the same extent by native and Mn-substituted enzyme. The temperature dependence of the relaxation times indicates that the shortening of the transverse relaxation time is determened by the lifetime of bound succinate, whereas the further shortening of the longitudinal relaxation time by the Mn-substituted enzyme is due to dipolar relaxation, i.e. to the interaction between Mn and the succinate protons. The distance between the Mn and the protons of succinate bound to the enzyme can be calculated from the relaxation time measurements and is 15,3 A. The dipolar interaction correlation time which is needed for the calculation of this distance, was found to be 3.5 X 10 minus 9 sec from the frequency dependence of T1. The transverse relaxation time of the C-6 proton of CTP is shortened to the same extent by both the native and Mn-substituted enzyme in D2O solutions of 0.02 M imidazole chloride (pH 7.0), 10 MINUS 3 M beta-mercaptoethanol, 0.2 mM ethylenediaminetetraacetic acid, and 2.5 mM carbamyl phosphate over the temperature 5-30 degrees. Since the temperature depencece of the relaxation time indicates the relaxation is not exchange limited, the manganese must be too distant from the bound CTP for an appreciable interaction to occur. This requires that the manganese be greater than 20A from the CTP. These results are used together with other available structural data to construct a schematic model for aspartate transcarbamylase.

A theoretical description of the new phases of liquidHe3

This paper reviews the theory of anisotropic superfluid phases and its application to the new A and B phases of liquid $^{3}\mathrm{He}$. It is tutorial in nature and advanced formal techniques are avoided; even the formalism of second quantization is not required. After an initial discussion of the Fermi-liquid theory of Landau and its application to the normal phase of liquid $^{3}\mathrm{He}$, the idea of instability against formation of Cooper pairs is introduced. The effective interaction in liquid $^{3}\mathrm{He}$ is considered, with emphasis on the spin-dependent interaction arising from virtual spin polarization of the medium ("spin fluctuation exchange"). Next, a self-contained discussion of the "weak-coupling" BCS theory as applied to anisotropic superfluids is given, with special attention to the "Ginzburg-Landau" region close to the transition temperature. Formulas are derived for the specific heat, spin susceptibility, normal density tensor, and static spin-dependent correlation properties of superfluids with both singlet and triplet pairing: In the triplet case the ideas of "spin superfluid velocity" and "spin superfluid density" are also introduced. After a preliminary comparison of the weak-coupling theory with experiment, it is shown that feedback effects due to the modification, by formation of Cooper pairs, of the effective interaction connected with spin fluctuation exchange can produce results which are qualitatively different from those of the weak-coupling theory. An attempt is made to reformulate recent graph-theoretical treatments of this phenomenon in a more elementary language, and considerations based on possible invariant forms of the free energy are also introduced. The properties of the so-called Anderson-Brinkman-Morel and Balian-Werthamer states, which are commonly identified with $^{3}\mathrm{He}$-A and B, respectively, are studied in detail. Next, the effects which tend to orient the Cooper pair wave function in a given experimental situation are discussed; in this context the form of the free energy terms arising from spatial variation of the wave function is explored. A semiphenomenological theory of the nuclear magnetic resonance properties is developed and applied in particular to the case of unsaturated cw resonance; the analogy with the Josephson effect is emphasized. The question of relaxation and linewidths is also briefly discussed. A partial account is given of the theory of finite-wavelength collective oscillations, with particular reference to first, second, and fourth sound and spin waves. The splitting of the A-normal transition in a magnetic field is considered, with special attention to the possibility it offers of testing theories of the "spin fluctuation" type. Finally, a brief assessment is made of the extent to which the current experimental data support the conventional identification of $^{3}\mathrm{He}$-A and B and the spin fluctuation theory, and some outstanding problems and possibilities are outlined. Subjects not discussed include "first-principles" theories of the effective interaction in $^{3}\mathrm{He}$ collective excitations in the "collisionless" regime, and the problem of ultrasonic absorption, "orbit waves," and the theory of the kinetic coefficients.

Structural and NMR properties of niobium dichalcogenides intercalated with post transition metals

The intercalation phase of the transition-metal dichalcogenide Nb${\mathrm{Se}}_{2}$, intercalated with Ga, In, Tl, Sn, and Pb, as well as Nb${\mathrm{S}}_{2}$, intercalated with In, have been prepared and studied by a variety of techniques. For most intercalates, single-intercalation-phase samples of the formula ${M}_{\frac{2}{3}}\mathrm{Nb}{X}_{2}$ were obtained, where $M$ is the intercalate and $X$ a chalcogen. The changes in the lattice parameters occurring upon intercalation have been determined from x-ray powder patterns. No superconducting transition was observed in any of the intercalated samples above 1.5 K. The microscopic properties were studied from 1.5 to 4.2 K using nuclear-magnetic-resonance (NMR) techniques, with the prime emphasis on the determination of the electric field gradients (EFG) at the Nb sites. For each intercalated sample the EFG was reduced by (35-60)% from that found in Nb${\mathrm{S}}_{2}$ and Nb${\mathrm{Se}}_{2}$. For the ${\mathrm{Tl}}_{\frac{2}{3}}\mathrm{Nb}{\mathrm{Se}}_{2}$ sample, the Nb line shape was fit by a single EFG while for all other intercalates at least two EFGs were needed to fit the Nb line shape, indicating two sites with inequivalent NMR properties. This change in the EFG at the Nb sites upon intercalation is attributed to charge transfer from the intercalated atoms into the conduction band of the layered compound. Knight-shift and spin-lattice relaxation-time measurements on the intercalate resonance indicate conduction-band behavior at the intercalate site but with a low density of states at the Fermi energy. The Sn M\"ossbauer line shape was studied in ${\mathrm{Sn}}_{\frac{2}{3}}\mathrm{Nb}{\mathrm{Se}}_{2}$. Only a single resonance was observed indicating a lack of any large quadrupole splitting as opposed to the two-line spectrum which has been observed for Sn in ${\mathrm{Sn}}_{1}$Ta${\mathrm{S}}_{2}$.

Synthesis of isomeric 11-hydroxy 11-methyl prostaglandins

The synthesis of several novel 11-substituted prostaglandins has been achieved from PGA 2 methyl ester from the marine coral Plexaura homomalla . The configuration of the substituents at position 11 is based on the nuclear magnetic resonance properties.

Proton nuclear magnetic resonance studies of histidine residues in rat and other rodent pancreatic ribonucleases. Effects of ph and inhibitors

Proton nuclear magnetic resonance spectra of the histidine residues in bovine and rat ribonuclease have been compared. The changes in chemical shift on titration and on binding of cytidine-3′-monophosphate and cytidine-2′-monophosphate have been followed. In the presence of the cytidine derivatives the spectra of both enzymes resemble each other more than those of the free enzymes. With these inhibitors, two histidines in rat ribonuclease exhibit the same p K values and shifts as the active site residues histidine 12 and 119 in the bovine enzyme. Their p K values in the inhibitor-free rat enzyme are about 0.4 higher than in the beef enzyme, which can be explained by the substitution at the entrance of the active site cleft of arginine 39 in the beef enzyme by serine in the rat enzyme. Rat ribonuclease contains one histidine with a rather high p K value of 7.6. The cytidine derivatives affect its chemical shift in exactly the same way as the shift of histidine 48 in bovine ribonuclease. The high p K value of this residue in rat ribonuclease can be explained by assuming a strong hydrogen bridge with glutamic acid 16. The other two histidines in rat ribonuclease have rather low p K values of 6.1 and 6.3. The histidine with a p K value of 6.3 has been assigned to position 105 and that with a p K value of 6.1 to position 73. The closer resemblance of the active sites of bovine and rat ribonuclease in the presence of inhibitors than in the inhibitor-free enzymes makes the concept of induced fit interesting from an evolutionary point of view. The characteristic downfield shift of the protonated form of histidine 119 in the complexes of bovine and rat ribonuclease with cytidine-3′-monophosphate is not observed with uridine-3′-monophosphate, suggesting non-identical binding of these pyrimidine nucleotides. Some preliminary results on the nuclear magnetic resonance properties of the histidine residues in coypu and chinchilla pancreatic ribonuclease have been obtained.

Nuclear spin relaxation in a single and double layer system of adsorbed water

The proton nuclear magnetic resonance (NMR) properties of single layer and double layer adsorbed water in a synthetic fluor montmorillonite are discussed. The continuous wave spectrum consists of a doublet and a narrow central line. The former is intrepreted in terms of random jumps between different possible molecular orientations in an ice-like structure. The latter is understood to be caused by molecules in two different sites undergoing different characteristic motions, with exchange occurring between the two sites. The spin-lattice relaxation is analyzed considering the uniaxial rotations which generate the doublet lineshape.

Isolation of ceramide-monomethylaminoethylphosphonate from the lipids of Tetrahymena pyriformis W

Ceramide-monomethylaminoethylphosphonate has been isolated for the first time from the lipids of Tetrahymena pyriformis W and characterized on the basis of its chromatographic mobility, chemical analysis, and infrared and nuclear magnetic resonance properties.

Relaxation magnetique nucleaire et proprietes magnetiques des alliages du systeme ( V1− χCrχ) Be2

Magnetic susceptibilities and nuclear magnetic resonance properties of V 51 and Be 9 isotopes are reported for (V 1−χCr χ)Be 2 alloys. 0,28 ⩽ x < 1. The susceptibilities are constant with temperature. The value of the square root of the nuclear spin lattice relaxation rate (T 1T) − 1 2 decrease from V 0,72Cr 0,28Be 2 to CrBe 2. The V 51 Knight shift increases with increasing CrBe 2 content. Relaxation rate and Knight shift are discussed in terms of the contributions from Fermi contact terms, sd exchange and orbital paramagnetism. The composition dependence of the NMR is interpreted in the simple rigid band.

Temperature Dependence of Hard-Sphere Interference Functions

It is shown in this paper that the Debye-Waller correction is important in the study of hard-sphere interference function IDW(q) for liquid metals. The calculated IDW(q) agree remarkably well with the experimental Iexptl(q) indicating the right trend for the temperature dependence. An evaluation has been also made of the electron transport and nuclear magnetic resonance properties for a number of liquid metals with the calculated IDW(q). The results show much better agreement with the corresponding experimental values than hitherto has been published.

Nuclear Magnetic Resonance in theLaX3Intermetallic Compounds

The ${\mathrm{La}}^{139}$ nuclear-magnetic-resonance (NMR) Knight shift and spin-lattice relaxation time (${T}_{1}$) in La${\mathrm{Pb}}_{3}$ were measured from 1.5 to 300\ifmmode^\circ\else\textdegree\fi{}K. The isotropic and anisotropic ${\mathrm{Pb}}^{207}$ Knight shifts were measured at 1.5, 4.2, and 77 \ifmmode^\circ\else\textdegree\fi{}K and ${T}_{1}$ was measured at 1.55\ifmmode^\circ\else\textdegree\fi{}K. Also presented are measurements of the La ${T}_{1}$ in La${\mathrm{In}}_{3}$ from 1.5 to 300\ifmmode^\circ\else\textdegree\fi{}K which are more complete than previously reported. These measurements are compared with previously reported measurements for La${\mathrm{Sn}}_{3}$. The ${\mathrm{La}}^{139}$ Knight shift (+0.010% at 4.2\ifmmode^\circ\else\textdegree\fi{}K) in La${\mathrm{Pb}}_{3}$ has a temperature dependence roughly five times that found in La${\mathrm{Sn}}_{3}$ and La${\mathrm{In}}_{3}$ even though the bulk susceptibility is considerably smaller. For La${\mathrm{Pb}}_{3}$, the La ${T}_{1}T$ product is nearly temperature independent (${T}_{1}T=0.59$ sec \ifmmode^\circ\else\textdegree\fi{}K at 4.2\ifmmode^\circ\else\textdegree\fi{}K) and is about half that found in La${\mathrm{Sn}}_{3}$. For La${\mathrm{In}}_{3}$, ${T}_{1}T$ increases by 50% between 1.5 and 300\ifmmode^\circ\else\textdegree\fi{}K and has a temperature dependence similar to La${\mathrm{Sn}}_{3}$. The isotropic and anisotropic Pb Knight shifts (${K}_{\mathrm{iso}}=+0.70%$ and $3{K}_{\mathrm{ax}}=+0.43%$ at 4.2\ifmmode^\circ\else\textdegree\fi{}K) are nearly temperature independent. The Pb relaxation time in La${\mathrm{Pb}}_{3}$ (${T}_{1}T=63\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ sec\ifmmode^\circ\else\textdegree\fi{}K) is about four times faster than in Pb metal, indicating a larger $s$-contact contribution than in Pb metal and a large negative Knight-shift component. The La NMR and bulk-susceptibility data are partitioned using the customary approximation for transition metals. We find the results for La${\mathrm{In}}_{3}$ and La${\mathrm{Sn}}_{3}$ are quite similar suggesting that in both these materials the La $d$-orbital susceptibility is much larger than the $d$-spin susceptibility and that exchange-enhancement effects are probably not important. For La${\mathrm{Pb}}_{3}$, $d$-orbital effects are less important than the $d$-spin contributions. In all three compounds the La $d$-spin contributions to the NMR properties and the bulk susceptibility are of similar magnitude.

Dielectric and nuclear magnetic resonance properties of ethylene oxide hydrate to 2 K

Dielectric and proton magnetic resonance properties of the clathrate hydrate of ethylene oxide (EO) between 2 and 270 K are reported. Arrhenius activation energies of reorientation are 32.4 kJ/mol for the water molecules, measured above 190 K, and 5.9 kJ/mol for encaged EO, measured below 40 K. The contribution of EO molecules to the equilibrium permittivity declines below 50 K. At 2 K the permittivity (4.1 ± 0.3) includes a large contribution from rotational oscillations of EO. The second moment of the proton absorption of EO in D2O hydrate reaches the rigid lattice value (11.4 ± 0.4 G2) only below 5 K, where a complex line structure from interaction of the four magnetically-isolated protons is resolved. Above 230 K, EO molecules effectively undergo isotropic rotation. The width of the dielectric absorption and the large temperature range of n.m.r. line-narrowing suggest considerable variability in the rotational freedom of EO in different cages, as expected from the presence of orientational disorder of the water molecules.

A Magnetic Resonance Study of Radical Recombination in Irradiated Cysteine Hydrochloride Monohydrate

Radical recombination reactions in samples of irradiated cysteine hydrochloride monohydrate are investigated, using electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopy. Radicals were induced by ultraviolet light and by γ-irradiation. Two phases can be identified in the crystals, and recombination rates of the sulphur radicals were found to be different in the two phases. One phase is believed to represent a glassy phase which shows unusual NMR properties, particularly at 393°K when vigorous motion appeared to average out almost all of the dipolar line width. This phase is not detected in anhydrous cysteine hydrochloride. Possible mechanisms of the recombination reactions are discussed, consistent with the experimentally determined activation energies in the two phases.

Thallium-205 Nuclear Magnetic Resonance Study of Pyruvate Kinase and Its Substrates: EVIDENCE FOR A SUBSTRATE-INDUCED CONFORMATIONAL CHANGE

Abstract A thallium-205 nuclear magnetic resonance (NMR) study of pyruvate kinase has been carried out. Shift and broadening of the 205T1 resonance have been observed upon binding of the thallous ion to the enzyme. Small changes in these parameters are observed upon binding of magnesium(II) to the enzyme with further changes arising from the binding of phosphoenolpyruvate, a substrate of the enzyme. The longitudinal (T1) and transverse (T2) relaxation times of 205T1 are dramatically affected by the presence of the paramagnetic manganous ion due to the existence of electronnuclear dipolar (for T1 and T2) and hyperfine (for T2 only) interactions. The distance between the monovalent (T1+) and divalent (Mn2+) activators of pyruvate kinase has been evaluated from the T1 values. In the pyruvate kinase-Mn(II) complex the average distance is 8.2 A whereas in the pyruvate kinase-Mn(II)-phosphoenolpyruvate it is 4.9 A. The change of the thallium to manganese distance upon binding of phosphoenolpyruvate is direct evidence for a substrate-induced conformational change. The thallous ion forms complexes with the substrates of pyruvate kinase (phosphoenolpyruvate, ATP, ADP, and pyruvate) in absence of the enzyme, which give rise to chemical shifts and broadenings of the 205T1 resonance. The line broadening is enhanced in presence of Mn(II) suggesting that the substrates form complexes having both a monovalent and a divalent ion. The possibilities of using the NMR properties of the nuclei of the alkali metal ions to probe macromolecular environment in the presence of paramagnetic ions are discussed. It appears that the properties of thallium-205 are uniquely suitable in this regard.