Heteronuclear Polarization Transfer under Steady-State Conditions: The INEPT-SSFP Experiment.

NMR finds a wide range of applications, ranging from fundamental chemistry to medical imaging. The technique, however, has an inherently low signal-to-noise ratio (SNR)─particularly when dealing with nuclei having low natural abundances and/or low γs. In these cases, sensitivity is often enhanced by methods that, similar to INEPT, transfer polarization from neighboring Hs via -couplings.

Probing the electronic structure and hydride occupancy in barium titanium oxyhydride through DFT-assisted solid-state NMR.

Perovskite-type oxhydrides such as BaTiOH exhibit mixed hydride ion and electron conduction and are an attractive class of materials for developing energy storage devices. However, the underlying mechanism of electric conductivity and its relation to the composition of the material remains unclear. Here we report detailed insights into the hydride local environment, the electronic structure and hydride conduction dynamics of barium titanium oxyhydride.

Separation of quadrupolar and paramagnetic shift interactions in high-resolution nuclear magnetic resonance of spinning powders.

Separation and correlation of the shift anisotropy and the first-order quadrupolar interaction of spin I = 1 nuclei under magic-angle spinning (MAS) are achieved by the phase-adjusted spinning sideband (PASS) nuclear magnetic resonance (NMR) experiment. Compared to methods for static samples, this approach has the benefit of higher sensitivity and resolution. Moreover, the PASS experiment has the advantage over previous MAS sequences in the ability to completely separate the shift anisotropy and first-order quadrupolar interactions.

Low-power synchronous helical pulse sequences for large anisotropic interactions in MAS NMR: Double-quantum excitation of N.

We develop a theoretical framework for a class of pulse sequences in the nuclear magnetic resonance (NMR) of rotating solids, which are applicable to nuclear spins with anisotropic interactions substantially larger than the spinning frequency, under conditions where the radiofrequency amplitude is smaller than or comparable to the spinning frequency. The treatment is based on average Hamiltonian theory and allows us to derive pulse sequences with well-defined relationships between the pulse parameters and spinning frequency for exciting specific coherences without the need for any detailed calculations. This framework is applied to the excitation of double-quantum spectra of N and is used both to evaluate the existing low-power pulse schemes and to predict the new ones, which we present here.

High-yield Production of Amyloid-β Peptide Enabled by a Customized Spider Silk Domain.

During storage in the silk gland, the N-terminal domain (NT) of spider silk proteins (spidroins) keeps the aggregation-prone repetitive region in solution at extreme concentrations. We observe that NTs from different spidroins have co-evolved with their respective repeat region, and now use an NT that is distantly related to previously used NTs, for efficient recombinant production of the amyloid-β peptide (Aβ) implicated in Alzheimer's disease. A designed variant of NT from Nephila clavipes flagelliform spidroin, which in nature allows production and storage of β-hairpin repeat segments, gives exceptionally high yields of different human Aβ variants as a solubility tag.

Artefact-free broadband 2D NMR for separation of quadrupolar and paramagnetic shift interactions.

Two new two-dimensional, broadband, solid-state NMR experiments for separating and correlating the quadrupolar and shift interactions of spin I=1 nuclei in paramagnetic systems are proposed. The new pulse sequences incorporate the short, high-power adiabatic pulses (SHAPs) into the shifting d-echo experiment of Walder et al. [J.

A spidroin-derived solubility tag enables controlled aggregation of a designed amyloid protein.

Amyloidogenesis is associated with more than 30 diseases, but the molecular mechanisms involved in cell toxicity and fibril formation remain largely unknown. The inherent tendency of amyloid-forming proteins to aggregate renders expression, purification, and experimental studies challenging. NT* is a solubility tag derived from a spider silk protein that was recently introduced for the production of several aggregation-prone peptides and proteins at high yields.

Structural studies of amyloid-β peptides: Unlocking the mechanism of aggregation and the associated toxicity.

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases worldwide. Formation of amyloid plaques consisting of amyloid-β peptides (Aβ) is one of the hallmarks of AD. Several lines of evidence have shown a correlation between the Aβ aggregation and the disease development.

Lunasin is a redox sensitive intrinsically disordered peptide with two transiently populated α-helical regions.

Lunasin is a 43 amino acid peptide with anti-cancer, antioxidant, anti-inflammatory and cholesterol-lowering properties. Although the mechanism of action of lunasin has been characterized to some extent, its exact three-dimensional structure as well as the function of the N-terminal sequence remains unknown. We established a novel method for the production of recombinant lunasin that allows efficient isotope labeling for NMR studies.