Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: HUMANGGP:001372 (ESR)
 7,313 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Near neutral pH, Fe(III) cytochrome c551 exhibits an ESR absorption due primarily to a single species with g values of 3.24, 2.06, and 1.48. These g values are somewhat different from those of horse heart cytochrome c and can be interpreted by the generalizations of Brautigan et al. [(1977) J. Biol. Chem. 252, 574] to be due to Fe binding by the imidazole anion of histidine rather than by neutral imidazole. The NMR spectrum of Fe(III) cytochrome c551 exhibits a number of hyperfine-shifted peaks whose pattern shows similarities to but many differences from that of horse heart cytochrome c. Variation in shifts of some of the peaks in the pH range 5--9 is ascribed to ionization of a somewhat buried propionic acid side chain (pK = 5.8) and to ionization of the N-terminal NH3+ group (pK = 7.7). At alkaline pH greater than 9.4, as shown by a variety of optical and ESR spectral changes, the Met-61 S ligand is replaced by other ligands.
 ...
PMID:1H NMR and ESR studies of oxidized cytochrome c551 from Pseudomonas aeruginosa. 3 1

Using a combination of ultraviolet-visible absorption, 1H NMR and ESR techniques we have established that N(1) of the imidazole and N(1) of the pyrimidine residues of bleomycin A2 bind to Cu(II) and Zn(II). The observations coupled with the earlier results that the alpha-amino group of the alpha-amino carboxamide function and the carbamoyl moiety are also Cu(II)-ligating groups makes it possible to reconstruct the detailed geometry and stereochemistry of the metal binding site of bleomycin A2.
 ...
PMID:A spectroscopic investigation of the metal binding site of bleomycin A2. The Cu(II) and Zn(II) derivatives. 7 23

The binding sites of some types of antithyroid drugs in the presence of the Fe(I)(NO)2 paramagnetic probe were investigated. Coordination behaviour in solution of different structured ligands was determined by means of ESR parameters and 13C FT-NMR spectra. Selective isotopic substitution with 15NO combined with computer simultation was used to elucidate overlapping ESR patterns. A correlation between chemical structure and antithyroid activity of the pharmacological bases is suggested.
 ...
PMID:Coordination behaviour of antithyroid drugs against the Fe(I)(NO)2 group in solution: ESR and FT-NMR study. 7 68

Cytochrome P-450 was solubilized from phenobarbital induced rabbit liver and purified by affinity chromatography. The longitudinal proton magnetic relaxation rates of this ferric, low-spin sample (as confirmed by ESR) in 20% glycerol aqueous solution are very large compared with low-spin methaemoglobin and myoglobin derivatives. Similarly high rates were measured in a deuterated solution using the aliphatic protons of glycerol as stereochemical markers, which strongly suggests that the haem iron in cytochrome P-450 is much more accessible to the solvent than in harmoglobin or myoglobin. Type I substate (Spasman) produced small but significant increases in NMR rates both in the H2O and in the 2H2O solution, while binding of aniline (Type II substrate) doubled the rates.
 ...
PMID:Haem accessibility in cytochrome P-450 from rabbit liver. A proton magnetic relaxation study by stereochemical probes. 18 34

The large number and diversity of anesthetic agents were evident to investigators 80 years ago, and suggested a physicochemical theory of anesthesia. Meyer and Overton were the first to offer a quantitative relationship between a physicochemical property and potency of anesthetic agents. They also focused attention on the lipid phase as the site of anesthetic action. Ferguson realized that the concentration of an agent at its site of action bears a generally unknown relation to the concentration in the external phase. However, at equilibrium the activity of an agent is the same in every phase, motivating Ferguson to suggest that activities rather than concentrations be used as indices of dosage. The critical-volume theory resulted from modification of the Meyer-Overton theory to include the molal volume of the anesthetic. The allowance for molal volume resulted initially from an attempt further to regularize the experimental data. The concept of a critical-volume fraction of anesthetic being necessary for narcosis was discussed in most detail by Mullins. Subsequently, the concept of the effect of the anesthetic has changed from filling of free space to expansion and fluidization of the membrane. The ability of pressure to cause excitant phenomena and antagonize anesthetics is predictable from the critical-volume theory and is therefore highly significant evidence. K. W. Miller and associates are perhaps most prominent in the recent quantification and formalization of the critical-volume theory and HPNS. The existence of a separate convulsant site(s) is suggested by the demonstration of significantly different compressibilities associated with anesthesia and convulsions. Work corroborating a separate convulsant site involved measurement of the partial molal volumes of a series of related convulsant and anesthetic ethers and calculation of each compound's solubility parameter. Multiple convulsant sites may exist, and these two methods may not have accessed the same site. Understanding the anesthetic-convulsant duality will have important practical application to deepwater diving, and may well offer important insight into the neurophysiologic and electrophysiologic effects of anesthetics. The application of ESR and NMR allows investigation at the molecular level of effects of anesthetics on biological and model membranes. Magnetic resonance techniques have generally supported the concept of membrane fluidization by anesthetics. Some investigators have recently attempted to displace the focus of attention from the lipid phase. However, the evidence is clearly against the aqueous-phase theory of Pauling and S.L. Miller. The microtubule theory of Allison and Nunn has not accumulated supporting evidence comparable to the lipid theories. Contradictory evidence makes any evaluation of this theory speculative. Additionally, the interspecies and intracellular variability of microtubules raises questions of the relevance of many studies...
 ...
PMID:Biophysical mechanisms of anesthetic action: historical perspective and review of current concepts. 18 56

The general mechanism for the antibiotic activities of the polymyxins and octapeptins has been elucidated by research using a broad range of experimental techniques. However, this phenomenon has not been described in detailed molecular terms, and this must be one of the major goals for future research in this area. Since 1947, when polymyxin was first isolated, there have been tremendous advances in our knowledge of membrane structure. The application of biophysical technology such as NMR, ESR, fluorescence spectroscopy, differential scanning calorimetry, and electron microscopy has been particularly valuable for studying model and biological membrane structures. It is these techniques which will provide a detailed molecular mechanism for the effects of these peptide antibiotics on membrane structure. In addition, the large number of antibiotic derivatives available should be exploited more extensively for structure-function correlations. The ultimate goal is to correlate the biological properties of these peptides with their effects on the physical properties of membranes and to rationalize these events in terms of lipid-peptide interactions.
 ...
PMID:Polymyxin and related peptide antibiotics. 19 81

Crystals of 6-oxybenzo(a)pyrene free radical, formed chemically from the hydroxy derivative of the carcinogen benzo(a)pyrene, can be solubilized in aqueous solutions of DNA and of caffeine. ESR spectral evidence indicate that the radicals exist as dispersed monomers associated with DNA and with caffeine. Comparison of NMR spin-lattice and spin-spin relaxation times in the protons of caffeine has given direct evidence that a part of the unpaired electron (at least 10(-4)) is transferred from the radical to the associated caffeine molecule. Simple consideration of Mulliken's charge transfer theory, however, leads to the conclusion that the intermolecular charge transfer is not likely to be a major source of stabilization energy of the complex.
 ...
PMID:Solubilization of 6-oxybenzo(a)pyrene radical by caffeine and DNA as studied by magnetic resonance. Observation of intermolecular charge transfer. 21 19

Bovine galactosyl transferase was found to utilize UDPglucose as a substrate and elicit disaccharide biosynthesis with glucose and N-acetylglucosamine as acceptors. The relative rate of glucosyl transferase with N-acetylglucosamine as acceptor was 0.3%, the rate for N-acetyllactosamine biosynthesis. This activity was also evidenced indirectly from NMR water proton relaxation experiments, and from Mn(II) ESR experiments. In direct experiments with radioactive UDPglucose, paper chromatography showed a product which migrated with cellobiose when glucose was the acceptor and a new, glucose-containing product which resulted when GlcNAc was the acceptor. Despite this marginally expanded specificity of the donor site, spin-label experiments with a covalently bound UDPgalactose analog reaffirmed the restrictive nature of the donor site against this non-glycosyl-like analog.
 ...
PMID:Glucosyl transferase activity of bovine galactosyl transferase. 21 25

We present the results of a Monte Carlo study of systems of hydrocarbon chains attached to a plane interface and interacting through hard core repulsive forces only. The chain-order parameters which we find in our studies are compared to experimental results (NMR and ESR). The role of "kink" states and the relevance of our studies to theoretical models are also discussed.
 ...
PMID:Monte Carlo studies of the hydrocarbon region of lipid bilayers. 90 87

Dielectric breakdown of intact erythrocytes and subsequent haemolysis in the presence of increasing concentrations of benzyl alcohol were investigated by means of an electrolytical discharge chamber and a hydrodynamic focusing Coulter Counter. Low concentrations of the drug stabilized human and bovine erythrocytes against haemolysis induced by dielectric breakdown of the cell membrane in isotonic solutions, while high concentrations caused lysis similar to hypotonic and mechanical haemolysis. The stabilizing effect of the drug on electrically induced haemolysis depends on the pulse length of the applied electric field. The critical dielectric breakdown voltage of the membranes of intact cells decreases progressively with increasing benzyl alcohol concentrations, at which the membrane is also more stabilized against electrical and osmotic haemolysis. Occasionally, an increase in the dielectric breakdown voltage is observed at drug concentrations at which lysis occurs. A similar depedence of the breakdown voltage on drug concentration was found for human erythrocyte ghost cells prepared by dielectric breakdown. The results are consistent with the electromechanical model suggested for the dielectric breakdwon mechanism and with the assumption of Metcalfe, using NMR and ESR techniques, that the fluidity of the membrane increases with increasing benzyl alcohol concentration.
 ...
PMID:Dielectric breakdown measurements of human and bovine erythrocyte membranes using benzyl alcohol as a probe molecule. 118 71


1 2 3 4 5 6 7 8 9 10 Next >>