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.

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.

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.

13C Nuclear Magnetic Resonance Investigation of Ethylene Homopolymers, Copolymers and Model Systems. Chemical Shifts and Relaxation Times

1979 ◽  
Vol 33 (2) ◽  
pp. 138-145 ◽  
Author(s):  
Leon Petrakis ◽  
K. S. Seshadri
Keyword(s):  
Chemical Shifts ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Model Systems ◽  
Spin Lattice Relaxation ◽  
Side Chain ◽  
Side Chains ◽  
Spin Lattice ◽  
13C Nuclear Magnetic Resonance ◽  
Magnetic Resonance Investigation

This is a report on the use of 13C NMR spectroscopy to study the structure of polyethylenes, polyethylene-olefin copolymers, and polyethylene model systems, through the observation of chemical shifts and spin-lattice relaxation times of individual carbons. Information is obtained on the type and numbers of side chains of polyethylenes from solution spectra at higher temperatures. The level of detectability of side chains is established at 2 side chain carbons per 1000 skeletal carbons. The observed chemical shifts are accounted for well by standard additivity schemes. The low-density polyethylenes show spectra which are distinctly different from high-density polyethylenes. The 13C-determined branch frequencies show the same general trend as the IR results, but it is also argued that the former are more accurate. Relaxation times of the various carbons of the model system C44 paraffin vary from 2.94 s for the backbone methylenes to 8.33 s for the terminal methyls to 11.11 s for α-methyls. Indicative of the behavior of olefin/polyethylene copolymers is the finding that all carbons of the copolymer have spin-lattice relaxation times of about 1.5 s, except for branch methyls which are 6 s. A series of polyethylenes at this high temperature shows relaxation times for the backbone methylene varying from 1.4 to 1.7 s, indicating that at this temperature, branching does not substantially affect the dynamic behavior of polyethylene.

Nuclear magnetic resonance study of conformation and dynamics in solution of p-(o-propyloxybenzamido)benzoate diethyl(2-hydroxyethyl)methylammonium bromide: a smooth muscle relaxant agent

1984 ◽  
Vol 62 (11) ◽  
pp. 2131-2135 ◽  
Author(s):  
Gianni Valensin ◽  
Lionello Pogliani ◽  
Mario Ghelardoni ◽  
Vittorio Pestellini ◽  
Alessandro Sega
Keyword(s):  
Title Compound ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Nuclear Magnetic Resonance Study ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Complete Analysis ◽  
Aromatic Rings ◽  
Spin Lattice ◽  
Smooth Muscle Relaxant

The relative conformation of the aromatic rings and the amide bridge as well as important details of the two side chains of the title compound in a DMSO-d6 solution have been established by use of non-selective and selective proton spin-lattice relaxation times coupled with nOe experiments. The complete analysis of 13C spin-lattice relaxation times has shown the main features of the dynamic behavior of the title compound.

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.

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