Biosynthetic13C Labeling of Aromatic Side Chains in Proteins for NMR Relaxation Measurements

2006 ◽  
Vol 128 (8) ◽  
pp. 2506-2507 ◽  
Author(s):  
Kaare Teilum ◽  
Ulrika Brath ◽  
Patrik Lundström ◽  
Mikael Akke
Keyword(s):  
Nmr Relaxation ◽  
Side Chains ◽  
Relaxation Measurements ◽  
Aromatic Side Chains

scholarly journals Freeze–Thaw Effect on Road Concrete Containing Blast Furnace Slag: NMR Relaxometry Investigations

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3288
Author(s):  
Liliana Maria Nicula ◽  
Ofelia Corbu ◽  
Ioan Ardelean ◽  
Andrei Victor Sandu ◽  
Mihai Iliescu ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Nmr Relaxation ◽  
Invasive Technique ◽  
Freeze Thaw ◽  
Nmr Relaxometry ◽  
Main Technique ◽  
Relaxation Measurements ◽  
Furnace Slag ◽  
Standard Techniques

The present work investigates the effect of freeze–thaw cycles on the porosity of three mixtures of road concrete containing blast furnace slag in comparison with two mixtures made with conventional materials. The main technique used in our investigations is nuclear magnetic resonance (NMR) relaxometry. This permitted the extraction of information with respect to the freeze–thaw effect on pore-size distribution, which influences both the mechanical strength and the molecular transport through the material. Moreover, by using this technique, the structure of the air voids was analyzed for the entire pore system in the cement paste and the aggregate particles. The samples under study were first dried in a vacuum oven and then saturated with water or cyclohexane where the distribution of the transverse relaxation times of the protons was recorded. The NMR relaxation measurements were performed on samples extracted from specimens maintained at 300 freeze–thaw cycles and on control samples extracted from specimens kept in water during the freeze–thaw period. Scanning Electron Microscopy (SEM) was used to analyze the microstructure of concrete samples in order to obtain information about the pore sizes and the distance between them. The results from the NMR relaxation measurements were consistent with those obtained by using standard techniques for determining the porosity and the freeze–thaw resistances. The investigations made it possible to establish the optimal composition of blast furnace slag that can be incorporated into road concrete compositions. This non-invasive technique can also complete standard techniques for assessing the porosity and the progress of internal cracks during the freeze–thaw test.

Privileged hydration sites in aromatic side chains: effect on conformational equilibrium

2017 ◽  
Vol 19 (42) ◽  
pp. 28684-28695 ◽  
Author(s):  
Belén Hernández ◽  
Fernando Pflüger ◽  
Manuel Dauchez ◽  
Mahmoud Ghomi
Keyword(s):  
Conformational Equilibrium ◽  
Theoretical Calculations ◽  
Side Chains ◽  
Aromatic Side Chains

The most energetically favourable hydration sites of aromatic (Phe, Tyr, Trp and His) side chains revealed by DFT-based theoretical calculations.

NMR relaxation measurements in solid H2 at low ortho-H2 concentrations

1977 ◽  
Vol 28 (5-6) ◽  
pp. 415-441 ◽  
Author(s):  
Robert F. Buzerak ◽  
Moses Chan ◽  
Horst Meyer
Keyword(s):  
Nmr Relaxation ◽  
Relaxation Measurements

Dipolar spectral densities from off-resonance 1H NMR relaxation measurements

1995 ◽  
Vol 233 (5-6) ◽  
pp. 545-549 ◽  
Author(s):  
H Desvaux ◽  
P Berthault ◽  
N Birlirakis
Keyword(s):  
1H Nmr ◽  
Nmr Relaxation ◽  
Spectral Densities ◽  
Relaxation Measurements

Enhancing signal-to-noise ratio and resolution in low-field NMR relaxation measurements using post-acquisition digital filters

2018 ◽  
Vol 57 (9) ◽  
pp. 616-625 ◽  
Author(s):  
Tatiana Monaretto ◽  
Andre Souza ◽  
Tiago Bueno Moraes ◽  
Victor Bertucci-Neto ◽  
Corinne Rondeau-Mouro ◽  
...  
Keyword(s):  
Digital Filters ◽  
Signal To Noise Ratio ◽  
Nmr Relaxation ◽  
Signal To Noise ◽  
Low Field ◽  
Relaxation Measurements ◽  
Low Field Nmr ◽  
Noise Ratio

scholarly journals Free Energy Landscape and Rate Estimation of the Aromatic Ring Flips in Basic Pancreatic Trypsin Inhibitor Using Metadynamics

2021 ◽  
Author(s):  
Pär Söderhjelm ◽  
Mandar Kulkarni
Keyword(s):  
Free Energy ◽  
Trypsin Inhibitor ◽  
Side Chain ◽  
Side Chains ◽  
Aromatic Residues ◽  
Basic Pancreatic Trypsin Inhibitor ◽  
Pancreatic Trypsin Inhibitor ◽  
Energy Surfaces ◽  
Aromatic Side Chains

Aromatic side-chains (phenylalanine and tyrosine) of a protein flip by 180° around the Cβ-Cγ axis (χ2 dihedral of side-chain) producing two symmetry-equivalent states. The ring-flip dynamics act as an NMR probe to understand local conformational fluctuations. Ring-flips are categorized as slow (ms onwards) or fast (ns to near ms) based on timescales accessible to NMR experiments. In this study, we investigated the ability of the infrequent metadynamics approach to discriminate between slow and fast ring-flips for eight individual aromatic side-chains (F4, Y10, Y21, F22, Y23, F33, Y35, F45) of basic pancreatic trypsin inhibitor (BPTI). Well-tempered metadynamics simulations were performed to observe ring-flipping free energy surfaces for all eight aromatic residues. The results indicate that χ2 as a standalone collective variable (CV) is not sufficient to classify fast and slow ring-flips. Most of the residues needed χ1 (N−Cχα) as a complementary CV, indicating the importance of librational motions in ring-flips. Multiple pathways and mechanisms were observed for residues F4, Y10, and F22. Recrossing events are observed for residues F22 and F33, indicating a possible role of friction effects in the ring-flipping. The results demonstrate the successful application of the metadynamics based approach to estimate ring-flip rates of aromatic residues in BPTI and identify certain limitations of the approach.

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