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At least 19 recordsLinked to original sources
PubMed1975

Comparison of membrane organization in mitochondria from yeast and rat liver by nuclear magnetic resonance spectroscopy.

Proton magnetic resonance (PMR) and carbon-13 magnetic resonance (CMR) spectra of intact, unsonicated yeast and rat liver motochondria show differences which may be correlated with the composition of the membranes. High resolution PMR and CMR signals in intact yeast mitochondria have been assigned to regions of fluid lipid-lipid interaction on the basis of spectra of extracted lipid and protein, and the temperature dependence of NMR signals from the intact membrane. PMR spectra suggest that about 20% of total yeast phospholipid is in regions where both intramolecular fatty acid chain mobility and lateral diffusion of entire phospholipid molecules are possible. No such regions apear to exist in rat liver mitochondria. For both yeast and rat liver mitochondria, comparison of PMR and CMR spectra suggests that about 50% of phospholipid appears to be in regions where intramolecular fatty acid chain motion is considerable, but lateral diffusion is restricted. The remaining phospholipid appears to have little inter- or intramolecular mobility. Since NMR observation of lipid extracts from membranes indicates that phospholipid-sterol interactions do not account for the spectra of intact mitochondria, these effects are interpreted in terms of extensive lipid-protein interactions.

Animals↗
PubMed1977

Organic phosphate binding to hemoglobin in intact human erythrocytes determined by 31P nuclear magnetic resonance spectroscopy.

Phosphorus nuclear magnetic resonance (31P NMR) spectroscopy was used to estimate the percent of 2,3-diphosphoglycerate and ATP bound to hemoglobin in intact human erythrocytes at 37 degrees C. Binding was assessed by comparing the chemical shifts (delta) of 2,3-diphosphoglycerate and of ATP observed in intact cells with the delta values of these organic phosphates determined in model solutions closely simulating intracellular conditions, in which percent binding was directly evaluated by membrane ultrafiltration. The results showed that the percent of bound 2,3-diphosphoglycerate in intact cells varied with pH, the state of oxygenation, and 2,3-diphosphoglycerate concentration. The values ranged from 33% in cells incubated with glucose in air at an intracellular pH of 7.2 to 100% in cells incubated with inosine in N2 at a pH of 6.75. At the same 2,3-diphosphoglycerate concentration, a greater percentage of the compound appeared to be bound in erythrocytes than in the closely simulated model system. ATP was not significantly bound to hemoglobin under any condition examined, but appeared to be strongly complexed to Mg2+ inside the erythrocyte. The binding percentages for both 2,3-diphosphoglycerate and ATP in intact cells estimated by 31P NMR spectroscopy were lower than those calculated by others from individual association constants determined for the binding of different ligands to hemoglobin.

Adenosine Triphosphate↗
PubMed1978

A hydrogen-deuterium exchange study of the amide protons of polymyxin B by nuclear-magnetic-resonance spectroscopy.

1. Proton magnetic resonance spectra at 270 MHz of polymyxin B, a cationic oligopeptide antibiotic, show the influence of the inorganic counteranion present in solution. 2. Hydrogen-deuterium exchange rates for the amide protons are of two types, depending on whether the anion is monovalent or polyvalent. Polyvalent anions catalyse the acid-catalysed reaction more than the monovalent anions. 3. The structure in solution was monitored using the proton signals of the amides, the phenylalanine aromatic protons, and the leucine methyl and gamma-CH protons in several polymyxin salts. The temperature coefficients of the chemical shifts of the N-H protons are used to identify two beta turns in the cyclic ring of polymyxin B. The variation in chemical shift of the N-H protons, the aromatic protons and the leucine protons are correlated with anionic size and electronegativity.

Amino Acid Sequence↗
PubMed1978

Quantitative determination of chlorpromazine. HCl in tablets, spansules, injectables, and bulk chemical by nuclear magnetic resonance spectroscopy.

A nuclear magnetic resonance (NMR) procedure is described for the quantitative analysis of chlorpromazine. HCl in bulk chemical as well as in final dosage forms--tablets, spansules, and injectables. The method is based on measurement of a characteristic signal of chlorpromazine relative to an internal standard. Three different internal standards are specified: Cyclohexane was selected because of the convenience and rapidity with which samples could be prepared for assay. Piperonal was used to verify the method and to show that precision and accuracy were not affected by the volatility of the cyclohexane. Tetramethylammonium bromide was used as an internal standard for Thorazine injectable. No interferences were found from stearates and other tablet excipients. The NMR procedure provides a simple, direct, and specific assay with a precision of +/- 1-2%.

Capsules↗
PubMed1977

Characterization of C-4-methylated sterols by pyridine-induced solvent shifts in proton magnetic resonance spectroscopy.

The proton magnetic resonance (PMR) spectra were measured in deuterochloroform (CDC13) and pyridine solutions for some 4-desmethyl, 4alpha-methyl, 4beta-methyl, and 4,4-dimethyl sterols related to 5alpha-cholestane series as well as for their C-3-oxo derivatives. The influence of pyridine, relative to CDC13, on methyl group chemical shifts was discusssed. The technique utilizing pyridine-induced solvent shifts in PMR spectroscopy was found useful in characterizing the individual classes of sterols.

Chloroform↗
PubMed1977

Strucutres of the capsular polysaccharides of Neisseria meningitidis as determined by 13C-nuclear magnetic resonance spectroscopy.

The application of 13C-nuclear magnetic resonance spectroscopy to the structural determination of the capsular polysaccharide antigens of Neisseria meningitidis is described. Complete assignments of the spectra of the polysaccharides of serogroups A, B, C, W-135, X and Y were made and were based mainly on previous assignments made for the monomer units of the respective polysaccharides. This technique provides information on all structural aspects of the polysaccharides including composition, mode of linkage, location of O-acetyl substituents, sequence, and conformation. In addition, nuclear magnetic resonance is nondestructive, extremely rapid, and has enormous potential in bacteriological research.

Acetylation↗
PubMed1978

Sphingomyelin multiple phase behavior as revealed by multinuclear magnetic resonance spectroscopy.

31P and 13C nuclear magnetic resonance (NMR) spectra are employed to study the phase behavior of bovine brain sphingomyelin as a function of temperature. The 31P NMR data suggest that, while at low temperatures sphingomyelin can form a lamellar phase, at physiological temperatures and higher the lamellar phase is unstable, and a new phase, best described as a hexagonal phase, is formed. Egg phosphatidylcholine is suggested to play an important role in stabilizing bilayers in natural membranes. Cholesterol also exhibits a sphingomyelin bilayer-stabilizing ability. The 13C NMR spectra suggest a gelling of the hydrocarbon chains of sphingomyelin at low temperature. Thus, bovine brain sphingomyelin undergoes both a gel to liquid-crystalline phase transition and a lamellar to nonlamellar transition.

Animals↗
PubMed1977

Structural studies on 2-acetamido-1-N-(4-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine and 2-acetamido-6-O-(alpha-L-fucopyranosyl)-1-N-(4-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine by 360-MHz proton-magnetic-resonance spectroscopy.

The 360-MHz proton magnetic resonance spectra of 2-acetamido-1-N-(4-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine (GlcNAcbeta1 leads to Asn) and 2-acetamido-6-O-(alpha-L-fucopyranosyl)-1-N-(4-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine (Fucalpha1 leads to 6GlcNAcbeta1 leads to Asn) in deuterium oxide were completely interpreted. The chemical shifts and coupling constants were refined by simulation of the spectra. By means of an adapted Karplus equation the pyranose ring conformation of the sugars was calculated. The change of the geminal coupling constant J6a,6b in the N-acetylglucosamine residue of Fucalpha1 leads to 6GlcNAcbeta1 leads to Asn with respect to GlcNAcbeta1 leads to Asn is proposed to be characteristic for the (1 leads to 6) glycosidic linkage.

Acetylglucosamine↗
PubMed1979

Hydrogen bonding in solution between the uracil ring and the peptide backbone demonstrated by nuclear magnetic resonance spectroscopy.

Proton and 13C nuclear magnetic resonance measurements indicate that uracil derivatives dissolved in chloroform bind to glycine and phenylalanine tripeptide derivatives through pairs of hydrogen bonds. The N(3)--H and C(4)=0 groups of the uracil ring appear to interact with the C=0 and N--H groups, respectively, of individual amino acid residues, suggesting a fundamental complementarity between uracil and the peptide backbone. The binding occurs in the same concentration range as the hydrogen bonding between derivatives of adenine and uracil under comparable conditions.

Glycine↗
PubMed1975

Nuclear magnetic resonance spectroscopy: reinvestigation of carbon-13 spin-lattice relaxation time measurements of amino acids.

The carbon-13 spin-lattice relaxation times (T1) of glycine have been measured as a function of pD and concentration. Contrary to previously reported findings, no significant dependence was observed on either pD or concentration. In addition, the T1 values reported here are much longer than those published earlier. The discrepancies arise from the presence of paramagnetic impurities in the earlier samples. For the carboxyl carbon, dipole-dipole relaxation is dominant in both D2O and H2O solution, and in H2O there is a significant intermolecular dipolar contribution. Proton and oxygen relaxation times have also been measured. These, along with the carbon relaxation data, allow a discussion of the dynamics of glycine in solution.

Amino Acids↗
PubMed1979

Investigation of the structure of the blue copper protein from Rhus vernicifera stellacyanin by 1H nuclear magnetic resonance spectroscopy.

The 270-MHz 1H nuclear magnetic resonance spectra of Cu(II), Cu(I), and apo-stellacyanin are reported and compared. The data indicate that little conformational change occurs on reduction of the protein or on removing the copper ion. In the aromatic region of the spectra of the holoprotein, resonances associated with two freely titrating histidines are observed. Two additional sharp resonances are observed in the spectra of the apostellacyanin which are tentatively assigned to additional histidines. This result requires that not more than two histidines can be ligands since there are only four histidines in the whole protein. The absence of methionine has been reported and is one of the possible causes for the difference between stellacyanin and the other copper blue proteins. A comparison of these data with those available for other blue copper proteins, in conjunction with the sequence information, leads to a proposed structure for the copper site in stellacyanin.

Apoproteins↗
PubMed1977

Investigation of the structure of bovine erythrocyte superoxide dismutase by 1H nuclear magnetic resonance spectroscopy.

The 270-MHz 1H nuclear magnetic resonance spectra of the apo, copper(I)-zinc(II), and copper(II)-zinc(II) forms of bovine erythrocyte superoxide dismutase (EC 1.15.1.1) are reported, and assignments of resonances to ten amino acid residues are proposed. The data require that at least four and probably six histidine residues serve as ligands to the metals in each subunit of the enzyme, consistent with x-ray diffraction results. The remaining assigned resonances are associated with His-19, His-41, Tyr-108, and the N-terminal N-acetyl group. The imidazole C(2)H of His-41 exchanges readily at pH greater than 8. The structural implications of the effect of the paramagnetic Cu(II) in the holoenzyme on the proton relaxation times are in reasonable accord with the data from x-ray diffraction studies.

Animals↗
PubMed1975

Interaction of Mg2+ ions with nucleoside triphosphates by phosphorus magnetic resonance spectroscopy.

The interaction of Mg2+ with nucleoside triphosphates: ATP, GTP, CTP and UTP has been studied by phosphorus magnetic resonance spectroscopy in aqueous solution. The results show that these four nucleotides behave similarly. Purine and Purimidine bases have almost no effect on the phosphate groups even in the N7 pK region of ATP and GTP. The Mg2+ ion binds not to the alpha and alpha but only to the beta phosphate group. The fixation is stronger at neutral pH than at acid pH.

Adenosine Triphosphatases↗
PubMed1977

Determination of enantiomeric homogeneity (optical purity) of cyclophosphamide by nuclear magnetic resonance spectroscopy.

The enantiomeric homogeneity of resolved samples of the chiral anticancer drug cyclophosphamide was evaluated directly by 1H and 31P nuclear magnetic resonance spectroscopy with the use of the optically active shift reagent tris-[3-(trifluoromethylhydroxymethylene)-d-camphorato]europlum(III). These measurements, in concert with optical rotatory dispersion spectroscopy, established that, for optically pure cyclophosphamide, [alphaD] = 2.3 +/- 0.2 degrees.

Cyclophosphamide↗
PubMed1978

Heterogeneity of the rhamnomannans from one strain of the human pathogen Sporothrix schenckii determined by 13C nuclear magnetic resonance spectroscopy.

The synthesis of different rhamnomannans in a strain of Sporothrix schenckii (1099.12) was shown by use of 13C nuclear magnetic resonance spectroscopy. Fractionation of a polysaccharide preparation from cells grown at 25 degrees C provided a neutral monorhamnosyl rhamnomannan and an acidic rhamnomannan containing 4-O-substituted glucuronic acid units and also (1 leads to 2)-linked dirhamnosyl side chains.

Magnetic Resonance Spectroscopy↗