Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q9UMR3 (NMR)
 150,598 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three metabolites of tritium-labeled mazindol were isolated from rat urine by the inverse isotope-dilution technique in which the labeled metabolites were synthesized by a second, smaller group of rats. These metabolites were isolated by Amberlite XAD-2 chromatography and silica gel column and preparative thin-layer chromatography. The major metabolite (II) was shown by mass spectrometry of its trimethylsilyl derivative. NMR spectroscopy, and degradation studies to be 5-(p-chlorophenyl)-2,5-dihydro-5-hydroxy-3H-imidazol(2,1-a)isoindol-3-one. A comparison of its mass spectrum with that of an authentic sample prepared from 1-(p-chlorophenyl)-3-ethoxy-1-methoxy-1H-isoindole and glycine ethyl ester confirmed the assignment. Metabolite III was shown by its mass spectrum, NMR spectrum, degradation, and analogy with metabolite II to be 5-(p-chlorophenyl)-2,5-dihydro-2,5-dihydroxy-3H-imidazo (2,1-a)isoindol-3-one. Only a small amount of metabolite IV was isolated as an artifact, 3-(p-chlorophenyl)-2-glycyl-3-methoxy-1-isoindolinone, as shown by its mass spectrum and degradation to 2-(p-chlorobenzoy)benzoic acid. The metabolite IV is believed to be the corresponding 3-hydroxy compound. Synthesis of IV by base-catalyzed hydrolysis of metabolite II supports the structural assignment. In addition, the facile conversion of synthetic IV into the corresponding 3-methoxy derivative by acidic methanol was also observed.
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PMID:Biotransformation of mazindol. I. Isolation and identification of some metabolites from rat urine. 0 31

220 MHz proton Fourier transform (FT) NMR with quadrature phase detection (QPD) technique is applied to observe largely hyperfine-shifted signals of various hemoproteins and hemoenzymes in ferric high-spin state. The binding of F-, OCN-, SCN-, and CH3OH to the ferric heme iron in high-spin state in various hemoproteins has been studied by the use of FT/QPD technique at 220 MHz. The binding of formate ion to metmyoglobin (metMb) has also been studied. The spectrum of the formate complex was compared with that of hemoglobin M Milwaukee where carboxylate groups are bound to the hemes of the beta subunits. The acid-base transition of ferric myoglobin (Mb) was confirmed by monitoring the pH-dependent shift of the heme side methyl signals with the reflection point at pH 9.1. This finding is analyzed on the basis of rapid exchange between alkaline (low spin) and acidic (high spin) forms accompanied by the dissociation and association of one proton in the ferric Mb. The structure of the heme environment of ferric horseradish peroxidase (HRP) was studied. The pH-dependent features of NMR spectra of the ferric enzyme and its complexes with cyanide and azide were discussed in terms of heme environmental structures, comparing with the case of metMb. The results were interpreted as follows: There exists an ionizable amino group near the heme responsible for the ligand binding reactions of the enzyme, which modulates the entry of external azide to the heme iron through protolytic equilibrium of this group. The pK value of this group was determined to be 5.9 by monitoring the pH-dependent shift of the heme peripheral methyl signals of the native enzyme, indicating that the group is probably a histidyl residue. Acid-alkaline transition of metMb was confirmed to associate with the proton dissociation of an iron-bound water molecule, whereas in HRP, pH-dependent spin state change characterized by pK 11 is attributed not to the simple protolytic reaction of the iron-bound water but to the direct coordination of an amino acid residue of the polypeptide chain to the ferric heme iron. Histidyl imidazole is a possible candidate for the new sixth iron ligand in alkaline peroxidase above pH 11. Interaction of HRP with electron donor(indolepropionic acid, IPA) was also studied. The hyperfine-shifted proton signals of the heme peripheral groups of the enzyme showed a small but significant shift with stepwise additions of IPA, indicating that the donor binds at a specific site of HRP. There results are interpreted in terms of the interaction between the enzyme and the donor at the heme edge site.
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PMID:Nuclear magnetic resonance studies of high-spin ferric hemoproteins. 2 54

1. From NMR, IR and visible absorption studies of 2'(or 3')-O-(2, 4, 6-trinitrophenyl)-adenosine 5'-triphosphate (TNP-ATP), 2'(or 3')-O-(2, 4, 6-trinitrophenyl) adenosine (TNP-Ad(, and 1-(2'-hydroxyethoxy)-2, 4, 6-trinitrobenzene (TNP-EG), it was concluded that there is an intramolecular interaction between the base and 2, 4, 6-trinitrophenyl (TNP) moieties in the TNP-ATP molecule. 2. A broad new absorption band was observed in the 530-630 nm region when excess indole was added to reaction mixtures containing TNP-ATP dissolved in 50% methanol or dimethyl sulfoxide. On addition of aromatic amino acid derivatives, methanol or dimethyl sulfoxide. On addition of aromatic amino acid derivatives, TNP-ATP and TNP-Ad underwent spectral shifts in the 400-550 nm region. The formation of a 1:1 complex apparently occurred between TNP-ATP and aromatic amino acid derivatives, and the complex with N-acetyltryptophan was stable in 50% methanol. The difference spectrum of TNP-EG vs. TNP-ATP closely resembled that induced by the addition of N-acetyltryptophan to the TNP-ATP solution. 3. The binding of 2'(or 3')-O-(2, 4, 6-trinitrophenyl)adenosine 5'-diphosphate (TNP-ADP) to heavy meromyosin (HMM) was studied by the rapid gel equilibrium method using Sephadex G-25. A dissociation constant of 1.4 muM and a maximum binding number of 1.8 were obtained in 0.15 M KCl, 10 mM MgCl2, and 50 mM Tris-HCl (pH 8.0) at 25 degrees. TNP-ADP bound to the enzyme caused a characteristic spectral shift in the visible region. This spectral shift was explained in terms of an interaction between tryptophanyl residues and the adenine base of TNP-ADP bound to the enzyme. TNP-ADP quenched the tryptophanyl fluorescence, but TNP-EG and TNP-Ad did not. In the presence of 6 M guanidine hydrochloride, TNP-ADP scarcely quenched the tryptophanyl fluorescence, its effect being comparable to that of TNP-Ad.
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PMID:2' (or 3')-O-(2, 4, 6-trinitrophenyl)adenosine 5'-triphosphate as a probe for the binding site of heavy meromyosin ATPase. 13 93

Deuterium NMR of 3alpha,12alpha-dihydroxy-7,7dideutero-5beta-cholanic acid was studied. Molcular sizes obtained from deuterium spin-lattice relaxation time (T1) data of 3alpha,12alpha-dihydroxy-7,7-dideutero-5beta-cholanoic acid in methanol and in water are in accordance with monometic and tetrameric structures in the two media, respectively. The deuterium T1 and intensity of 3alpha,12alpha-dihydroxy-7,7-dideutero-5beta-cholanoic acid in aqueous solution at pH 8.0--8.8 were studied as functions of NcC1 and lecithin concentrations. The results indicated that tetramers are in equilibrium with larger aggregates when secondary micelles are formed in the precense of NaC1, and that 3alpha,12alpha-dihydroxy-7,7-dideutero-5beta-cholanoic acid forms mixed micelles with lecithin with a molecular ratio of 2 : 3.
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PMID:The nature of bile salt micelles as studied by deuterium NMR. 18 Oct 71

A study of the effects of various storage conditions on the rate and products of degradation of the quinoline methanol antimalarial agent, alpha-[(dibutylamino)methyl]-6,8-dichloro-2-(3',4'-dichlorophenyl)-4-quinoline methanol, was undertaken. The degradation was followed by high-pressure liquid chromatography and TLC in oxygenated and deoxygenated methanol, ethanol, chloroform, and chloroform-heptane mixtures under UV and laboratory fluorescent lighting irradiation, as well as in the absence of light. The kinetics of degradation confirmed the major catalyzing factor to be UV irradiation. The compound was stable in the absence of light and reasonably stable under fluorescent lighting both in the presence and absence of oxygen. The degradation resulted in a major product, 6,8-dichloro-2-(3',4'-dichlorophenyl)-4-quinoline-carboxaldehyde, whose structure was confirmed by elemental analysis and IR, NMR, and mass spectral data.
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PMID:Photolytic degradation of alpha-[(dibutylamino)methyl]-6,8-dichloro-2-(3',4'-dichlorophenyl)-4-quinoline methanol: an experimental antimalarial. 24 28

Two chemical degradations of clavulanic acid are described which are useful for locating label in 14C-clavulanate. In the first, the beta-hydroxyethylidene side chain of p-bromobenzyl clavulanate is removed by ozonolysis to give p-bromobenzyl (2R, 5R)-3,7-dioxo-4-oxa-1-azabicyclo [3.2.0] heptane-2-carboxylate. The second involves the reaction of p-bromobenzyl clavulanate with dibenzylamine in methanol, to isolate the three beta-lactam carbons as methyl trans-3-(N-N-dibenzyl)amino acrylate. These techniques were used to degrade clavulanic acid derived from fermentations fed with 2-14C-acetate or universally 14C-labelled glycerol. The amount of label retained in the degradation products was in agreement with the distribution of 13C in clavulanic acid derived from 2-13C-acetate, or 1,3-13C2-glycerol, as observed by 13C-NMR.
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PMID:Studies on the biosynthesis of clavulanic acid. II. Chemical degradations of 14C-labelled clavulanic acid. 52 82

The binding of lasalocid A (X537A) to Pr(III) in methanol has been studied by lasalocid fluorescence, circular dichroism, and 1H and 13C NMR spectroscopy. It is clear that in addition to a mono complex, bis and tris complexes are also formed. Values of the binding constants and spectral properties of the various complexes have been determined by computer fitting of the binding isotherms. The Pr (III) ion binds only at the salicylic "head" of the lasalocid A, in stark contrast with other known structures. The lasalocid A appears to have an "open" conformation in these complexes. The relevance of these results to the structure and conformation of the Ca(II) complex is discussed. The first order rate constant for the dissociation of the tris complex has also been determined.
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PMID:Interaction of antibiotic lasalocid A (X537A) with praseodymium(III) in methanol. 69 78

The osmotic permeability coefficient (Lp) for human red cells has been reported to depend on the osmolality of the suspending solution. These results are also consistent with the view that the value of Lp depends on flow rectification. In this report an NMR method is used to measure the dependence of water exchange times at constant cell volume on osmolality. Our results indicate that the diffusion water permeability is constant over a large range of osmolality (300-1000 mosM) produced by the permeable solutes urea, methanol, ethanol, and glycerol. The results support the view that the apparent dependence of Lp on osmolality is due to flow rectification.
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PMID:Diffusional water permeability of red cells. Independence on osmolality. 83 92

The conformations of 12 dinucleoside monophosphates containing N4-phenylcytidine (CPh) or N4(beta-naphthyl)cytidine (CbetaN) residues have been studied, using circular dichroic spectroscopy. The following compounds had aqueous spectra resembling their parent compounds, which lacked the modifying aromatic substituent: CPhpU, CbetaNpU, UpCPh, UpCbetaN, CPhpG, CbetaNpG, GpCPh, and CPhpA. The spectra of GpCbetaN and ApCbetaN were almost the reverse of the unmodified compounds, while CbetaNpA and ApCPh were intermediary in character. When the spectra were run in methanol, all major differences between the modified and unmodified compounds disappeared. This result suggested that the differences observed in aqueous solution were the result of stacking interactions between the aromatic ring and a neighboring purine. When the aromatic ring was naphthalene, the modified cytidine occupied the 3'-terminal position, and, when the purine was adenine, the effect was enhanced. These conclusions were supported by a consideration of chemical shifts in the 1H NMR spectra of ApCbetaN, and GpCbetaN, as compared to those of the unmodified compounds and CbetaNpG. A study of molecular models of ApCbetaN and GpCbetaN revealed a unique conformation in which the purine rotates to a syn position, in order to allow a close stacking interaction with the naphthalene ring. No such conformation is available for CbetaNpA and CbetaNpG, and the best partial stacking interaction occurs in a conformation with the purine in the anti conformation. The base-displacement theory of carcinogenesis (Levine, A. F., Fink, L. M., Weinstein, I. B., and Grunberger, D. (1974), Cancer Res. 34, 319) describes the conformational change resulting from the attachment of a bulky aromatic residue at the 8 position of guanine in RNA or DNA, and attributes biological importance to the event. The changes that occur upon substitution of the amino group of cytosine differ in detail from the above, but would be expected to produce similar biological results. Base-displacement effects need not be limited, therefore, to a particular substitution position in a nucleic acid.
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PMID:Conformation of aromatic-substituted dinucleoside monophosphates: an extension of the base-displacement theory of carcinogenesis. 84 14

The reaction of X-537A (XH) with Co(2+) in methanol to form the complex CoX(+) has been studied fluorometrically to determine the equilibrium constant as a function of temperature. The effect of complexation on the proton NMR spectrum of the X-537A was studied to determine the kinetics of complex formation. Comparing the data for the reaction XM(+) leads to X(-) + M(2+) in methanol at 25 degrees for several M(2+) we find that the equilibrium constants increase in the order CoX(+) less than MnX(+) and span only a factor of 5 while the rate constants increase in the order NiX(+) less than CoX(+) less than MnX(+) and span a factor of more than 100.
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PMID:Ion binding by X-537A. Equilibrium and rate of complexation of Co(2+) in methanol. 95 52


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