Abstracted/indexed

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 a 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.

Natural photosynthetic reaction centers (RCs) are built up by two parallel branches of cofactors. While photosystem II and purple bacterial RCs selectively use 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 similarly distinguished to those in purple bacterial RCs (Schulten et al., 2002; Biochemistry 41, 8708). Alternative reasons are discussed.

This work presents systematic methodological study of one of the types of the nuclear magnetic resonance experiments that enables study of molecular dynamics on a millisecond timescale. A modification of a standard experiment was suggested that excludes possible artefacts and distortions. It has been demonstrated that the standard experiment reveals slow overall motion of proteins in a rigid crystal lattice, whereas the artefact-free experimental setup demonstrates that the proteins are rigid.

We studied spin dynamics in nuclear spin systems at low magnetic fields, where strong coupling among nuclear spins of the same kind, here ¹³C, is expected. Such conditions are known to be favorable for coherent polarization transfer. However, to our surprise, interactions with other nuclei, i.e., protons, lead to a breakdown of the strong coupling conditions. By using a two-field nuclear magnetic resonance approach, we can manipulate low field-spin dynamics and reintroduce strong coupling.

Magnetic resonance detectors require a high degree of precision to be useful. Their design must e.g. carefully weigh field strength and field homogeneity to find the best compromise. Here we show that inverse computational design is a viable method to find such a trade-off. Apart from the electromagnetic field solution, the simulation program also determines the boundary between insulating and conducting material and moves the material boundaries around until the compromise is best satisfied.

Dipolar electron paramagnetic resonance spectroscopy methods such as DEER provide data on how proteins change shape, thus giving detailed insight into how proteins work. We present DeerLab, a comprehensive open-source software for reliably analyzing the associated data. The software implements a series of theoretical and algorithmic innovations and thereby improves the quality and reproducibility of data analysis.

The stable, two-atomic radical NO, which is an important biophysical messenger, was studied with magnetic resonance methods. Caused by its specific electronic configuration, it has sensor properties: its magnetic moment sensitively depends on its environment and restricted mobility therein. The interaction with solvents or solid phases can thus be quantified. Encapsulating the radical in the nearly spherical cage of modified C₆₀ fullerenes is a perfect situation to study this effect.

Resonant pulses in a spin-lock frame are used to select parts of the rf-field distribution in NMR experiments. Such pulses can be implemented in a straightforward way and arbitrarily shaped pulses can be used. We show an application of such pulses in homonuclear decoupling where restricting the amplitude distribution of the rf field leads to improved performance.