Preprints  

We present a tutorial on the cross-polarization experiment, which has been the main method of magnetization transfer in solid-state NMR for decades. We explain the principles of its volume-selective performance in the presence of magic angle spinning and radiofrequency field inhomogeneity and the decrease of efficiency with increasing sample rotation frequency.

Detailed balance is a principle that underlies some fundamental laws in physics. Motivated to analyze asymmetry in three-site NMR relaxation-exchange maps, 2D Monte-Carlo simulations of vacancy and gas diffusion were executed. They show that detailed balance is violated for a small fraction of molecules diffusing in confinement. This fraction exchanges coherently in circles between three relaxation pools. It is understood to be a manifestation of diffusion eigenmodes or diffusive resonance.

This paper describes the design and implementation of new technology for nuclear magnetic resonance which is a technique used to understand molecular structure and dynamics of many systems. The spherical sample container and its apparatus introduced in this paper is used to perform initial proof of principle experiments at cryogenic temperatures. Further development of this technology will facilitate more flexibility in magnetic resonance experiments.

Hyperpolarization methods offer the possibility to overcome the inherent sensitivity limits of nuclear magnetic resonance (NMR) given by the thermal Boltzmann spin distribution. The radio-frequency (RF) pulses to monitor the hyperpolarization process alter it by depleting the created magnetization. Possible corrections are simulated with a rate-equation model containing a single source and relaxation rate. The accuracy is demonstrated experimentally, enabling the use of larger flip angles.

A novel cell-free protein synthesis system called eCells produces amino acids based on specific isotopes using low-cost precursors. The system selectively labels methyl groups; i.e valine and leucine with high efficiency. eCells achieve high levels of ¹³C incorporation and deuteration in protein preparations, making them suitable for NMR experiments of large protein complexes. It is easy to prepare and can be scaled up in volume, making it a promising tool for protein production and NMR studies.

We show that the field profile of the solid effect in liquids is rich in dynamical information, including about time scales of molecular diffusion. We develop a general theoretical framework for extracting this information through quantitative fits to the experimental data. Unusual peaks in the enhancement field profile, which resemble thermal mixing but are not related to it, are demonstrated to arise in liquids under some conditions. These additionally restrict the dynamical parameters.

Since its discovery 65 years ago, the solid-state DNP effect has been rationalized in terms of mixing of the Zeeman energy levels. Before becoming aware of this explanation, Erb, Motchane and Uebersfeld proposed a dynamical equation to make sense of their experiments. Here we provide a formal justification of their phenomenological equation. The result is a different way of thinking about the solid-state effect with novel implications about the effect in liquids.

The magic angle spinning (MAS) technique of solid state NMR requires samples to be rapidly rotated within a magnetic field. The rotation rate speed record is 150 kHz, or 9 million RPM, and hence MAS turbines hold the world rotation speed record for extended objects. The containers holding the samples are made of the strongest materials known, to be able to withstand the excessive centrifugal forces. To overcome the speed limit, this paper delineates a way to do so using an optical tweezers setup

Providing evidence that proteins are dynamical molecules is a major contribution of solution NMR to structural biology. But the classical experiments to measure dynamics can only be applied to small proteins. This is regretful, because larger proteins often display conformational changes in which dynamics plays a functional role. We show here that dynamic information can be extracted from HSQC NMR spectra using a computational approach. Such spectra are widely available also for larger proteins.

We show here that information about protein molecular dynamics can be directly extracted out of a single NMR spectrum. Understanding protein dynamics is essential to understanding its function, energetics and biology. We hope that this contribution helps bring this insight to a much broader application field and audience community than previously possible.

The demonstration of the Finite Pulse Radio Frequency Driven Recoupling experiment was firstly published over the past 20 years. Since it has become one of the used experiments. In this article we consider that experiment using other theoretical and simulated approaches with respect to the previous works. These approaches help us to understand more clearly the influence of each part of that experiment and to see how exactly the spin system is evaluated during it.

We recently added 2D NMR spectroscopy to the well-established techniques able to obtain information on the process of unfolding using resonances of residues in the hydrophobic core of a protein. We asked whether a detailed analysis of the individual stability curves could provide additional site-specific information. By monitoring both cold and heat denaturation of individual residues we convincingly demonstrate that the two unfolding processes are intrinsically different.

Nowadays, almost all MRI technique used in clinical applications are based on a Fourier transformation of the raw data. Alternative non-Fourier magnetic resonance imaging techniques can offer some advantages under certain conditions. SPatio-temporal ENcoding (SPEN) is a non-Fourier method that usually employs frequency-swept radio frequency pulses and can give good images in inhomogeneous magnetic fields. In this work we show how one can improve this technique by using quadratic gradients.