Faculty Opinions recommendation of Functional dynamics of response regulators using NMR relaxation techniques.

Abstract Proteins are dynamic in nature and exist in a set of equilibrium conformations on various timescale motions. The flexibility of proteins governs various biological functions, and therefore elucidation of such functional dynamics is essential. In this context, we have studied the structure–dynamics–stability–activity relationship of bacteriophage T7 lysozyme/endolysin (T7L) native-state ensemble in the pH range of 6–8. Our studies established that T7L native state is conformationally heterogeneous, as several residues of its C-terminal half are present in two conformations (major and minor) in the slow exchange time scale of nuclear magnetic resonance (NMR). Structural and dynamic studies suggested that the residues belonging to minor conformations do exhibit native-like structural and dynamic features. Furthermore, the NMR relaxation experiments unraveled that the native state is highly dynamic and the dynamic behavior is regulated by the pH, as the pH 6 conformation exhibited enhanced dynamics compared with pH 7 and 8. The stability measurements and cell-based activity studies on T7L indicated that the native protein at pH 6 is ∼2 kcal less stable and is ∼50% less active than those of pH 7 and 8. A comprehensive analysis of the T7L active site, unfolding initiation sites and the residues with altered dynamics outlined that the attenuation of stability and activity is a resultant of its enhanced dynamic properties, which, in turn, can be attributed to the protonation/deprotonation of its partially buried His residues. Our study on T7L structure–dynamics–activity paradigm could assist in engineering novel amidase-based endolysins with enhanced activity and stability over a broad pH range.

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Solid-state 2H NMR relaxation illuminates functional dynamics of retinal cofactor in membrane activation of rhodopsin

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1014692108 ◽

2011 ◽

Vol 108 (20) ◽

pp. 8263-8268 ◽

Cited By ~ 40

Author(s):

A. V. Struts ◽

G. F. J. Salgado ◽

M. F. Brown

Keyword(s):

Solid State ◽

Nmr Relaxation ◽

2H Nmr ◽

Functional Dynamics

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New Insight into Li+ Dynamics in Lithium Bimetal Phosphate

Journal of The Electrochemical Society ◽

10.1149/1945-7111/ac4544 ◽

2021 ◽

Author(s):

Laurence Savignac ◽

John M. Griffin ◽

Steen Brian Schougaard

Keyword(s):

Electronic Conductivity ◽

Nmr Relaxation ◽

Structural Instability ◽

Electrochemical Performances ◽

Relaxation Techniques ◽

Transition Mechanism ◽

Expected Gain ◽

Multiple Processes ◽

Particle Level ◽

Structural Contribution

Abstract Substitution of iron by other transition metals within the remarkably stable olivine framework is of interest considering the expected gain in energy density. However, manganese rich olivine materials suffer from sluggish redox kinetics, leading to electrochemical performances at high current densities which are below expectations. The source of the kinetic limitations is not clear, with multiple processes having been proposed, including low bulk electronic conductivity, structural instability of Mn3+ and a phase transition mechanism. This study employed 7Li MAS NMR relaxation techniques to indirectly probe Li+ dynamics using various stoichiometry of chemically prepared LixMnyFe1-yPO4 (0 ≤ (x, y) ≤ 1). Focusing on the particle level, the aim was to understand how the different crystal phases, alongside the Mn structural contribution, influence Li+ transport at each stage of the oxidation process. Significantly, the formation of an olivine solid solution with vacancies within this progression gave rise to a faster 7Li transverse relaxation derived from superior Li+ motion.

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Experimental study of the structure I clathrate hydrate of trimethylene oxide by adiabatic calorimetry

Canadian Journal of Chemistry ◽

10.1139/v83-016 ◽

1983 ◽

Vol 61 (1) ◽

pp. 92-96 ◽

Cited By ~ 6

Author(s):

John Comper ◽

André Quesnel ◽

Colin A. Fyfe ◽

Robert K. Boyd

Keyword(s):

Adiabatic Calorimetry ◽

Nmr Relaxation ◽

Thermal Anomaly ◽

Far Infrared ◽

Clathrate Hydrate ◽

Relaxation Techniques ◽

Temperature Range ◽

Relaxation Measurements ◽

Trimethylene Oxide ◽

Order Of Magnitude

The structure I clathrate hydrate of trimethylene oxide (TMO), of composition 6TMO:46H2O, has been studied by adiabatic calorimetry over the temperature range 85–270 K. A thermal anomaly, with the appearance of a classical λ-transition, was observed between about 140–170 K. This anomaly was reproducible, provided precautions were taken against supercooling. No evidence for such a transition has been observed in previous studies using dynamic relaxation techniques (dielectric and nmr relaxation). The temperature range of this anomaly is close to the melting point of a known TMO-rich eutectic, but evidence is presented which argues against interpretation of the present observations in these terms. The previous relaxation measurements indicated a transition involving mobility of the TMO guest, centred at about 100 K. In the present work, the only evidence of this transition consisted of a much worse (order of magnitude) precision in the measured heat capacities in this temperature range. Thermal equilibration is known to be extremely slow in this system. The transition observed in the present work at higher temperatures must therefore correspond to some restructuring of the water host, and this may be connected with anomalous results obtained previously for the far infrared absorptions of water in the TMO clathrate hydrate.

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