Molecular determinants for drug-receptor interactions. 8. Anisotropic and internal motions in morphine, nalorphine, oxymorphone, naloxone and naltrexone in aqueous solution by carbon-13 NMR spin-lattice relaxation times

1989 ◽  
Vol 130 (1-3) ◽  
pp. 335-343 ◽  
Author(s):  
Antonio Grassi ◽  
Bruno Perly ◽  
Giuseppe C. Pappalardo
Keyword(s):  
Aqueous Solution ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Internal Motions ◽  
Molecular Determinants ◽  
Receptor Interactions ◽  
Drug Receptor

14N Nuclear Magnetic Resonance Relaxation of the Nitrate Ion and Ion Pairing in Aqueous Solution

1995 ◽  
Vol 48 (2) ◽  
pp. 207 ◽  
Author(s):  
G Owens ◽  
P Guarilloff ◽  
BJ Steel ◽  
T Kurucsev
Keyword(s):  
Aqueous Solution ◽  
Ion Pairs ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Metal Nitrate ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Fast Exchange ◽  
Resonance Relaxation ◽  
Two State Model

14 N n.m.r. spin-lattice relaxation times of four metal nitrate salts were measured as a function of concentration in aqueous solution. The concentration dependence of T1 was attributed to the formation of ion pairs with increasing concentration in these solutions. The T1 data, allowing for viscosity corrections, were treated by a two-state model of 'free' and 'bound' nitrate ions and to both possibilities of slow and fast exchange between the two states. In the equilibrium expressions estimates of the relevant activity coefficients were included. The slow nitrate exchange mechanism was favoured and the values obtained for this particular mechanism compared well with those derived from alternative measurements.

N.M.R. studies on myelin basic protein. IV. 13C N.M.R. of the peptide encephalitogenic in the guinea pig

1980 ◽  
Vol 33 (11) ◽  
pp. 2411 ◽  
Author(s):  
SA Margetson ◽  
WJ Moore
Keyword(s):  
Aqueous Solution ◽  
Guinea Pig ◽  
Basic Protein ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Side Chain ◽  
Aromatic Rings ◽  
Ph Titration ◽  
Spin Lattice

The encephalitogenic nonapeptide Phe1-Ser2-Trp3-Gly4-Ala5-Glu6-Gly7-Gln8- Lys9 and its [D-Ala5] analogue have been studied in aqueous solution by 13C n.m.r. spectroscopy. The resonances of all the carbons have been assigned and their pH profiles measured. The expected conformational differences are indicated by only subtle differences in long-range pH titration shifts. The spin-lattice relaxation times T1 of all the protonated carbons of the [L-Ala5] nonapeptide have been measured at 25°C. Analysis of these data in terms of effective correlation times for side-chain mobilities suggests restricted motions for the side chains of Glu6 and Gln8 and the aromatic rings of Phe1 and Trp3.

A Carbon-13 Spin-Lattice Relaxation Studies of Simple Alkylsulfates and Alkylsulfonates in Aqueous Solution

1983 ◽  
Vol 38 (10) ◽  
pp. 1149-1151
Author(s):  
Kazuhiro Matsushita ◽  
Yukimasa Terada ◽  
Tadayoshi Yoshida ◽  
Hirofumi Okabayashi
Keyword(s):  
Aqueous Solution ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Polar Group ◽  
Progressive Decrease ◽  
Methyl Group ◽  
Critical Micelle Concentrations ◽  
Spin Lattice ◽  
Relaxation Studies

Abstract The C-13 spin-lattice relaxation times (T1) of a series of short-chain n-alkylsulfates and sulfonates in D2O solutions were measured at various concentrations. Even for ethylsulfate and n-propylsulfonate ions, inflections, due to association, in the reciprocal of the T1 vs. the inverse concentration plots were observed. The critical micelle concentrations (CMC's) of ethyl and butylsulfates are 3.0 and 2.5 mol/l, respectively, and those of propyl and butylsulfonate 2.3 and 1.9 mol/l, respectively. For the simple alkylsulfates, below the CMC a progressive decrease in T1 from the terminal methyl group towards the polar group was observed.

Molecular Mobility of Sucrose in Aqueous Solution Studied by 13C NMR Relaxation

1993 ◽  
Vol 48 (5-6) ◽  
pp. 407-413 ◽  
Author(s):  
D. Girlich ◽  
H.-D Lüdemann
Keyword(s):  
Aqueous Solution ◽  
Concentration Dependence ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Rotational Dynamics ◽  
Spin Lattice Relaxation ◽  
Rotational Mobility ◽  
Spin Lattice ◽  
The Ideal

Abstract From the temperature and concentration dependence of the 13C spin lattice relaxation times of the 12 carbon atoms of the sucrose molecule the rotational dynamics of the sugar molecules are determined. No indication for conformational mobility of the rings is found. The exocyclic hydroxymethyl groups possess extra mobility. The models used for the description are critically discussed. The temperature dependence of the rotational mobility is described by a VTF equation. The concentration dependence of the ideal glass transition temperature To for this mobility is derived.

Proton spin–lattice relaxation in a solid protein Streptomyces subtilisin inhibitor. Enhancement of segmental motions by adsorbed water

1988 ◽  
Vol 66 (8) ◽  
pp. 2014-2017 ◽  
Author(s):  
K. Akasaka ◽  
K. Takegoshi ◽  
T. Terao ◽  
S. Ganapathy
Keyword(s):  
Relaxation Process ◽  
Relaxation Times ◽  
Adsorbed Water ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Internal Motions ◽  
Subtilisin Inhibitor ◽  
Group Rotations

Proton spin–lattice relaxation times (T1) were measured on a protein Streptomyces subtilisin inhibitor, in the solid state, in the presence and the absence of adsorbed 2H2O in the temperature range between −170 and 100 °C at 30 and 60 MHz. In both samples, a common relaxation process is attributed to the methyl group rotations of amino acid side chains which show minimum values of T1 of 0.11 s at −105 °C at 30 MHz and 0.23 s at −80 °C at 60 MHz. In the presence of adsorbed 2H2O, another, effective relaxation process was found above 0°C, showing a minimum value of T1 of 0.12 s at about 80 °C at 60 MHz. The latter relaxation process was attributed to internal motions of exposed peptide segments, a large part of which is located in the crucial enzyme-binding region of the inhibitor.

Dynamics of Liquid Crystals by Means of 2 H-NMR: a Comparison between 4,4'-bis(hexyloxy)azoxybenzene and the Derivative Pd(II) Complex AZPAC

1998 ◽  
Vol 53 (6-7) ◽  
pp. 427-435 ◽  
Author(s):  
Lucia Calucci ◽  
Claudia Forte ◽  
Marco Geppi ◽  
Carlo Alberto Veracini
Keyword(s):  
Pulse Sequence ◽  
Rotational Diffusion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Molecular Motions ◽  
Rotational Model ◽  
Spin Lattice ◽  
Internal Motions ◽  
Nematic Phases

Abstract In the present work we report a molecular dynamics investigation of the two mesogens 4,4'-bis(hexyloxy)azoxybenzene (HL) and its Pd(II) acetylacetonate derivative Azpac in their nematic phases. Deuterium Zeeman and quadrupolar spin-lattice relaxation times have been measured at 46.04 MHz on two isotopomers of Azpac (Azpac-d4 and Azpac-d26 , deuteriated on the aromatic core and on the alkoxy chains, respectively) and on HL-d4 , an isotopomer of HL partially deuteriated on the aromatic core, by means of the Wimperis pulse sequence. The spectral densities obtained from the measured relaxation times are discussed in terms of internal and overall molecular motions. A small step rotational diffusion model for the overall molecular motions, superimposed on a free rotational model for internal motions, allowed diffusion coefficients for molecular spinning and tumbling and for phenyl ring rotations to be derived for HL; the same models were used in describing the dynamics of Azpac.

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