Recent  

There is growing interest in mapping exchange dynamics between Watson–Crick and Hoogsteen conformations across different DNA contexts. However, current methods are ill-suited for measurements at a large scale because they require isotopically enriched samples. We report that Hoogsteen dynamics can be measured on unlabeled samples using 1H CEST experiments, which have higher throughput and lower cost relative to conventional methods and also provide new insights into Hoogsteen dynamics.

Novel electron spin resonance (ESR) detectors based on voltage-controlled oscillators (VCOs) have been attracting attention, mainly due to the possibility of integrating the whole ESR spectrometer onto a single printed circuit board at relatively low cost while maintaining a performance comparable to commercial solutions. We present an experimental setup where the signal is detected as a change in VCO oscillation amplitude, along with in-depth theoretical analysis of the novel readout scheme.

The original theories of NMR relaxation by Felix Bloch are exposed and explicated, thereby connecting these marginalized but important scientific papers with the new modern approaches.

Electron paramagnetic resonance (EPR) spectroscopy is the method of choice to investigate and quantify paramagnetic species. We present the application of an unconventional EPR detection method, rapid-scan EPR, to enhance the sensitivity on an improved design of a miniaturized EPR spectrometer implemented on a silicon microchip. Due to its size, it may be integrated into complex and harsh sample environments, enabling in situ or operando EPR measurements that have previously been inaccessible.

A straightforward line shape analysis of the ¹³C NMR spectra of [2-¹³C]sodium acetate can be used to indirectly evaluate the ¹³H polarization of the CH₃ group and likely entire samples in the case of rapid and homogeneous ¹³H–¹H spin diffusion. The results are potentially advantageous for polarizers that lack ¹H radiofrequency hardware, measurements that are influenced by radiation damping or large background signals, or where acquisition of thermal equilibrium spectra is not feasible.

Kidney stones (KSs) are a major health problem in industrialized countries. The study of KSs is presently at the heart of a concerted multidisciplinary axis of research involving physicians, physical chemists and spectroscopists. In this contribution, an in-depth structural description of KSs is proposed by implementing a combination of multinuclear and multidimensional solid-state NMR methodology.

The overall aim of the study is to provide a basis from which to improve the ability of tamoxifen family drugs to reduce the activity of a secondary target protein, calmodulin, during tumour development. The main conclusion is that the binding of a tamoxifen analogue is quite unlike that of other anti-calmodulin compounds in that two drug molecules bring the two domains of calmodulin into close proximity, but they are not fixed in orientation relative to the protein.

The HSQC experiment developed by Bodenhausen and Ruben is a cornerstone for modern NMR. When used in the field of metabolomics, the common practice of decoupling in the proton dimension limits the acquisition time and hence the resolution. Here, we present a virtual decoupling method to maintain both spectral simplicity and resolution, and demonstrate how it increases information content with the zebra mussel metabolome as an example.

We develop an exact analytical description of spinning sideband intensities in magic-angle spinning NMR, e.g., for 13C CSA. This can be used in spectral fitting to obtain tensor parameters and plays out its advantage in the analysis of orientation effects in non-isotropic samples. We present an improved approach to process data obtained with the simple syncMAS experiment, which is powerful but not very popular due to the as yet not very transparent and difficult data analysis.

We use the theory of magnetostatic reciprocity to compute manufacturable solutions of complex magnet geometries, establishing a quantitative metric for the placement and subsequent orientation of discrete pieces of permanent magnetic material. This leads to self-assembled micro-magnets, adjustable magnetic arrays, and an unbounded magnetic field intensity in a small volume, despite realistic modelling of complex material behaviours.

Multidimensional NMR relaxation experiments provide a powerful means of studying protein dynamics but typically require long acquisition times. Here, we combine two approaches that individually shorten the length of the experiment: accordion spectroscopy and non-uniform sampling (NUS). We extract relaxation rate constants by applying maximum likelihood estimation of sparse exponential modes modeled on the accordion–NUS interferograms, resulting in time savings by a factor of roughly 10.

Nuclear magnetic resonance spectroscopy is at the forefront of analytical methods used in organic chemistry and phytochemistry. Multiplet structure deconvolution has been revisited in the perspective of a robust integration in the computer-assisted workflow of 1D spectra analysis. New features include the management of coupling partners with spin > 1/2, second-order effects and partial signal overlap.

Unlike rigid folded proteins, intrinsically disordered proteins (IDPs) exist as an ensemble of dynamically interconverting structures. Cross-correlated spin-relaxation experiments are particularly suited to characterize the structural dynamics of IDPs as they encode a protein's structural memory. By translating diffusion models of folded proteins to segmental motions in IDPs, we define and assess a sensitive experimental measure for the presence of anisotropic dynamics in the protein backbone.

NMR represents a key spectroscopic technique for studying intrinsically disordered proteins (IDPs) that lack a stable three-dimensional structure. We present a set of NMR experiments tailored for proline residues, which are highly abundant in IDPs. The novel experiments have very interesting properties for the investigation of IDPs of increasing complexity.

The radio-frequency (rf) field amplitude in solid-state NMR probes changes over the sample volume, i.e. different parts of the sample will experience different nutation frequencies. If the sample is rotated inside the coil as it is typical for magic angle spinning in solid-state NMR, such a position-dependent inhomogeneity leads to an additional time dependence of the rf field amplitude. We show that such time-dependent modulations do not play an important role in many experiments.

Sample rotation around the magic angle averages out the dipolar couplings in homonuclear spin systems in a first-order approximation. However, in higher orders, residual coupling terms remain and lead to a broadening of the spectral lines. We investigate the source of this broadening and the effects on the powder line shape in small spin systems with and without chemical shifts. We show that one can expect different scaling behavior as a function of the spinning frequency for the two cases.

In drug discovery, ready access to accurate atomic resolution information revealing conformations and dynamics of novel small molecules in solution guides rational design to optimize drug potency and physical chemistry. We developed an efficient integration of molecular dynamics calculations and visualization protocols with NMR conformational analysis of free ligands in solution. Agreement between experiment and theory inspires confidence in prospective computational analysis of new designs.

Isotope filters are pivotal for studying interactions between labelled and unlabeled moieties by NMR. We present an isotope filter method to complement existing filters and attenuate undesired signals that escaped them. This advance will readily facilitate molecular studies of binding events or post-translational modifications by NMR.

The transfer of polarization from protons to half-integer spin quadrupolar nuclei provides insights into the proximities between these nuclei. We analyse the best transfers at 20 and 62 kHz MAS obtained with RINEPT and PRESTO recouplings using adiabatic or composite π pulses. The 1H magnetization is best transferred using PRESTO-R22,7,2 (180) or -R16,6,7 (270,90) at 20 or 62 kHz MAS, respectively, and RINEPT-SR4,2,1 (270,90).

This publication presents research in biomolecular NMR, spin hyperpolarisation and spin chemistry. Robert Kaptein made key contributions to magnetic resonance and proposed the radical pair mechanism for chemically induced dynamic nuclear polarisation (CIDNP). He developed laser CIDNP and computational methods for protein structure determination. He is known for studying the lac repressor and its DNA complexes. He played a leading role in establishing the NMR large-scale facilities in Europe.

An approach is described for formulating the kinetic master equations of the time evolution of hyperpolarized NMR signals in reacting (bio)chemical systems. We take a stepwise approach to formulate mathematical models of enzyme systems that agree with standard descriptions of (bio)chemical kinetics while remaining capable of describing the time evolution of magnetization described by the Bloch–McConnell equations.

The use of hyperpolarized species, i.e., species whose nuclear polarization is transiently multiplied by several orders of magnitude, can perfectly be combined with the use of benchtop NMR spectrometers. In particular, laser-polarized ¹²⁹Xe, due to its large chemical shift range and the proximity of its resonance frequency to ¹³C, can be observed on a non-dedicated low-field spectrometer. Detection of low amounts of molecules can be achieved using NMR techniques based on chemical exchange.