NMR of sedimented, fibrillized, silica-entrapped and microcrystalline (metallo)proteins

Studying the Conformation of a Silaffin-Derived Pentalysine Peptide Embedded in Bioinspired Silica using Solution and Dynamic Nuclear Polarization Magic-Angle Spinning NMR

“…Q 3 species at -102 ppm. Moreover, 1 H- 29 Si HETCOR spectra of silica prepared without PL12 (data not shown) show no such cross peaks at 2.9 ppm confirming that these peaks represent magnetization transfer from peptide protons to the silica. Similar interactions between glycine CH 2 protons (adjacent to amine) and Q 4 sites in silica 51 and between lysine residues in intact T. pseudonana and biogenic silica formed 24 were reported before.…”

“…PL12-silica particles were washed and analyzed using MAS NMR at room temperature and at 100K using DNPenhanced MAS NMR measurements. The silicon species in the final product were characterized using direct excitation and cross polarization 29 Si MAS NMR experiments ( Figure S2 in the SI). Typical Q 4 , Q 3 and Q 2 bands in silica (where Q n represents known silicon species of the form Si-(OSi) n OH 4-n ) were observed in the spectra at − 112 ppm, − 102 ppm and − 92 ppm, respectively.…”

“…Chemical shift perturbations along the backbone and sidechains were linked to respective changes in conformation and proximity of residues to silica [24][25][26] . Similarly, recent highresolution MAS NMR studies of enzymes entrapped in porous silica has examined the effects of confinement on the structure and functionality of proteins [27][28][29][30] .…”

“…DNP MAS NMR was also implemented for 1D and 2D 13 C and 29 Si measurements in unlabeled samples, relieving the need for elaborate and tedious sample labeling [40][41][42][43][44][45] . However, rapid deployment of the technique for extensive structural 2 characterization in biological systems is still hampered by low-resolution spectra [46][47] with some exceptions reported [48][49][50] .…”

Biosilica and bioinspired silica studied by solid-state NMR

“…[95,96] Improved experimental design, also based on a more accurate computational description of larger and larger spin systems, [97] has led to improved transfer efficiencies and resolution. [98][99][100][101][102][103][104] The physical condition of a sample is a key determinant for NMR resolution, with crystalline preparation usually yielding more resolved spectra [105]. However, the most interesting targets for solid state NMR are precisely those that are harder (or impossible) to obtain in crystalline form, such as membrane proteins, [5][6][7][106][107][108][109] protein assemblies [110][111][112][113][114], pathological aggregates [57][58][59][60] and fibrils [119][120][121][122][123]3,[124][125][126].…”