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Intramolecular motions in proteins are one of the important factors that determine their biological activity and interactions with molecules of biological importance. Magnetic relaxation of 15 N amide nuclei allows one to monitor motions of protein backbone over a wide range of time scales. 15 N{ 1 H} nuclear Overhauser effect is essential for the identification of fast backbone motions in proteins. Therefore, exact measurements of NOE values and their accuracies are critical for determining the picosecond time scale of protein backbone. Measurement of dynamic NOE allows for the determination of NOE values and their probable errors defined by any sound criterion of nonlinear regression methods. The dynamic NOE measurements can be readily applied for non-deuterated or deuterated proteins in both HSQC and TROSY-type experiments. Comparison of the dynamic NOE method with commonly implied steady-state NOE is presented in measurements performed at three magnetic field strengths. It is also shown that improperly set NOE measurement cannot be restored with correction factors reported in the literature.

Simple and convenient method of protein dynamics evaluation from the insufficient experimental 15 N relaxation data is presented basing on the ratios, products, and differences of longitudinal and transverse 15 N relaxation rates obtained at a single magnetic field. Firstly, the proposed approach allows evaluating overall tumbling correlation time (nanosecond time scale). Next, local parameters of the model-free approach characterizing local mobility of backbone amide N-H vectors on two different time scales, S 2 and R ex , can be elucidated. The generalized order parameter, S 2 , describes motions on the time scale faster than the overall tumbling correlation time (pico- to nanoseconds), while the chemical exchange term, R ex , identifies processes slower than the overall tumbling correlation time (micro- to milliseconds). Advantages and disadvantages of different methods of data handling are thoroughly discussed.

(15) N spin-relaxation rates are demonstrated to provide critical information about the long-range structure and internal motions of membrane proteins. Combined with an improved calculation method, the relaxation-rate-derived structure of the 283-residue human voltage-dependent anion channel revealed an anisotropically shaped barrel with a rigidly attached N-terminal helix. Our study thus establishes an NMR spectroscopic approach to determine the structure and dynamics of mammalian membrane proteins at high accuracy and resolution., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The integral polytopic membrane protein TSPO is the target for numerous endogenous and synthetic ligands. However, the affinity of many ligands is influenced by a common polymorphism in TSPO, in which an alanine at position 147 is replaced by threonine, thereby complicating the use of several radioligands for clinical diagnosis. In contrast, the best-characterized TSPO ligand (R)-PK11195 binds with similar affinity to both variants of mitochondrial TSPO (wild-type and A147T variant). Here we report the (1)H, (13)C, (15)N backbone and side-chain resonance assignment of the A147T polymorph of TSPO from Mus Musculus in complex with (R)-PK11195 in DPC detergent micelles. More than 90 % of all resonances were sequence-specifically assigned, demonstrating the ability to obtain high-quality spectral data for both the backbone and the side-chains of medically relevant integral membrane proteins.