Abstracted/indexed

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.

We introduce ssNMRlib, a library of pulse sequences and jython scripts for user-friendly setup and acquisition of solids-state NMR experiments. ssNMRlib facilitates all steps of data acquisition, including calibration of various pulse-sequence parameters and semi-automatic setup of even complex high-dimensional experiments, using an intuitive graphical user interface, launched directly within Bruker's Topspin acquisition program.

Natural photosynthetic reaction centers (RCs) are build up by two parallel branches of cofactors. While photosystem II and purple bacterial RCs use selectively one branch for light-driven electron transfer, photosystem I, as also shown here, is using both branches. Comparing NMR chemical shifts, we shown that the two donor cofactors in photosystem I are similar distinguished than those in purple bacterial RCs (Schulten et al., 2002 Biochemistry 41, 8708). Alternative reasons are discussed.

This work is discussing NMR experiments, which make use of coherent spin evolution at level-anti crossings. In this work, we provide a common description of such phenomena (hopefully, a reasonably simple one), which is illustrated by a number of examples from various subfields of NMR.

This work presents systematic methodological study of one of the types of the Nuclear Magnetic Resonance experiments that enables studying molecular dynamics on a millisecond time scale. A modification of a standard experiment was suggested that excludes possible artifacts and distortions. It has been demonstrated that the standard experiment reveals slow overall motion of proteins in a rigid crystal lattice, while the artefact-free experimental setup demonstrates that the proteins are rigid.

The sensitivity of magnetic resonance imaging can be increased by coupling of the less sensitive nuclear spins which are excited at radio-frequencies to unpaired electron spins of radicals which are excited at microwave frequencies. Here we demonstrate how an Fabry-Perot type microwave resonance structure can be used to significantly enhance the polarization transfer from electron to water proton nuclear spins under constant flow conditions for imaging applications at 1.5 T.

Through a series of DEER measurements on two Gd-rulers, with Gd-Gd distances of 2.1 and 6.0 nm, we show that artefacts commonly observed when measuring short distances can be eliminated by avoiding excitation of the central transition by both the pump and observer pulses. By using a wideband induction mode sample-holder at 94 GHz, we demonstrate that high quality DEER measurements will become possible using Gd spin labels at sub-uM concentrations, with implications for in-cell DEER measurements.

Here we demonstrate that Electron Spin Resonance (ESR) spectroscopy at millikelvin temperatures can be performed with a spectrometer comprised of a thin-film superconducting resonator and Josephson Parametric Amplifier (JPA) with sufficient bandwidth to detect Electron Spin Echo Envelope Modulation (ESEEM) while maintaining high spin-detection sensitivity.

With a pulsed dipolar EPR technique named Double Electron-Electron Resonance, we measure nanometer distances between spin labels attached to biomolecules. If more than one spin type is present (A and B), we can separately address AA, AB and BB distances via distinct spectroscopic channels, increasing the information content per sample. Here we investigate the appearance of unwanted channel crosstalks and suggest ways to identify and suppress them, thereby increasing signal fidelity.

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.