Polarised neutron scattering from dynamic polarised nuclei 1972-2022.

With the inauguration of the small-angle instrument D11 of the Institute Laue-Langevin (ILL) in September 1972 neutron scattering revolutionized methods of contrast variation. Very soon D11 was oversubscribed by proposals relying on isotopic substitution of hydrogen isotopes. At the same time in Oxford first experiments of polarised neutron diffraction from dynamic polarised protons in lanthanum magnesium nitrate crystals demonstrated the great utility of this approach.

Polarized proton spin density images the tyrosyl radical locations in bovine liver catalase.

A tyrosyl radical, as part of the amino acid chain of bovine liver catalase, supports dynamic proton spin polarization (DNP). Finding the position of the tyrosyl radical within the macromolecule relies on the accumulation of proton polarization close to it, which is readily observed by polarized neutron scattering. The nuclear scattering amplitude due to the polarization of protons less than 10 Å distant from the tyrosyl radical is ten times larger than the amplitude of magnetic neutron scattering from an unpaired polarized electron of the same radical.

Inside the bulk of magnetic nanocomposites: I am not what I am.

An unexpected and not always easily discernible feature in the picture of magnetic neutron scattering is widening the outlook on micromagnetic architecture [Mettus & Michels (2015). , 1437-1450].

A first low-resolution difference Fourier map of phosphorus in a membrane protein from near-edge anomalous diffraction.

Crystal diffraction of three membrane proteins (cytochrome bc(1) complex, sarcoplasmic reticulum Ca(2+) ATPase, ADP-ATP carrier) and of one nucleoprotein complex (leucyl tRNA synthetase bound to tRNAleu, leuRS:tRNAleu) was tested at wavelengths near the X-ray K-absorption edge of phosphorus using a new set-up for soft X-ray diffraction at the beamline ID01 of the ESRF. The best result was obtained from crystals of Ca(2+) ATPase [adenosin-5'-(beta,gamma-methylene) triphosphate complex] which diffracted out to 7 A resolution. Data were recorded at a wavelength at which the real resonant scattering factor of phosphorus reaches the extreme value of -20 electron units.

Small-angle scattering and its interplay with crystallography, contrast variation in SAXS and SANS.

Methods of contrast variation are tools that are essential in macromolecular structure research. Anomalous dispersion of X-ray diffraction is widely used in protein crystallography. Recent attempts to extend this method to native resonant labels like sulfur and phosphorus are promising.