scholarly journals How Much Entropy Is Contained in NMR Relaxation Parameters?

2021 ◽  
Author(s):  
Falk Hoffmann ◽  
Frans A. A. Mulder ◽  
Lars V. Schäfer
Keyword(s):  
Nmr Relaxation ◽  
Relaxation Parameters

Influence of depyritization on NMR relaxation parameters of Aleksinac oil shale kerogen

Fuel ◽  
1998 ◽  
Vol 77 (9-10) ◽  
pp. 1001-1003 ◽  
Author(s):  
Zoran Ẑujović ◽  
Radivoje Srejić ◽  
Dušan Vučelić ◽  
Branimir Jovančićević ◽  
Dragomir Vitorović
Keyword(s):  
Oil Shale ◽  
Nmr Relaxation ◽  
Relaxation Parameters

scholarly journals Determination of hydrogen exchange and relaxation parameters in PHIP complexes at micromolar concentrations

2021 ◽  
Author(s):  
Lisanne Sellies ◽  
Ruud L. E. G. Aspers ◽  
Marco Tessari
Keyword(s):  
Small Molecules ◽  
Hydrogen Exchange ◽  
Nmr Relaxation ◽  
Para Hydrogen ◽  
Natural Extracts ◽  
Relaxation Parameters ◽  
Selective Inversion ◽  
High Concentrations ◽  
Nmr Signals

Abstract. Non-hydrogenative Para-Hydrogen Induced Polarization (PHIP) is a fast, efficient and relatively inexpensive approach to enhance Nuclear Magnetic Resonance (NMR) signals of small molecules in solution. The efficiency of this technique depends on the interplay of NMR relaxation and kinetic processes, which, at high concentrations, can be characterized by selective inversion experiments. However, in the case of dilute solutions this approach is clearly not viable. Here, we present alternative PHIP-based NMR experiments to determine hydrogen and hydrides’ relaxation parameters as well as the rate constants for p-H2 association and dissociation from asymmetric PHIP complexes at micromolar concentrations. Access to these parameters is necessary to understand and improve the PHIP enhancements of (dilute) substrates present in, for instance, biofluids and natural extracts.

scholarly journals How much entropy is contained in NMR relaxation parameters?

2021 ◽  
Author(s):  
Falk Hoffmann ◽  
Frans A. A. Mulder ◽  
Lars V. Schäfer
Keyword(s):  
Time Scales ◽  
Nmr Relaxation ◽  
Md Simulations ◽  
Side Chain ◽  
Thermodynamic Quantities ◽  
T4 Lysozyme ◽  
Time Dynamics ◽  
Relaxation Parameters ◽  
Relaxation Experiments ◽  
Short Time

Solution-state NMR relaxation experiments are the cornerstone to study internalprotein dynamics at atomic resolution on time scales that are faster than the overallrotational tumbling time,τR. Since the motions described by NMR relaxation pa-rameters are connected to thermodynamic quantities like conformational entropies, thequestion arises how much of the total entropy is contained within this tumbling time.Using all-atom molecular dynamics (MD) simulations of T4 lysozyme, we found thatentropy build-up is rather fast for the backbone, such that the majority of the entropyis indeed contained in the short-time dynamics. In contrast, the contribution of slowdynamics of side chains on time scales beyondτRon the side chain conformationalentropy is significant and should be taken into account for the extraction of accuratethermodynamic properties.

Menstrual Variation of Normal Breast NMR Relaxation Parameters

1985 ◽  
Vol 9 (5) ◽  
pp. 875-879 ◽  
Author(s):  
Thomas R. Nelson ◽  
Dolores H. Pretorius ◽  
Lewis M. Schiffer
Keyword(s):  
Nmr Relaxation ◽  
Normal Breast ◽  
Relaxation Parameters
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