Reduction of Inhomogeneous Line Broadening in Two-Dimensional High-Resolution MAS NMR Spectra of Molecules Attached to Swelled Resins in Solid-Phase Synthesis

The Chemical Shift Index method applied to resin‐bound peptides

“…Coupling constants cannot be assessed easily on resin‐bound peptides, as the line widths of the order of 20 Hz exceed the expected coupling constants. We therefore implemented a scaling procedure of the coupling constant vs. chemical shift evolution (21), and found both for κ = 4 or κ = 8, coupling constant values of the order of 8 Hz. The absence of typical contacts both in NOE and ROE spectra, and the averaged coupling constants, lead us to conclude that the peptide sequences on the resin can sample all sterically allowed regions of conformational space.…”

“…in both dimensions, 1024 × 256 complex points and a mixing time of 80 ms. ROESY spectra with mixing times of 100 and 300 ms and similar spectral parameters were recorded on a Bruker DMX 600 MHz spectrometer. We also recorded a scaled DQF‐COSY experiment in order to verify the coupling constants in the indirect dimension (see text), with κ = 4 or 8, and 128 complex points in the t 1 dimension (21).…”

Selenium-Linking Strategy for Traceless Solid-Phase Synthesis: Direct Loading, Aliphatic C−H Bond Formation upon Cleavage and Reaction Monitoring by Gradient MAS NMR Spectroscopy

“…Information about coupling constants in poorly resolved spectra may be obtained from f2 projections of 2D-JRES spectra or from a 2D-E.COSY variant . However, by use of an HR-MAS probehead equipped with a magic angle pulsed field gradient coil, it was found that for these relatively high loaded resin samples sufficient structural information was achieved with fast 2D-COSY45 and optionally 2D-HSQC and 2D-HMBC experiments using gradient coherence selection.…”

COSY Cross-Peaks from 1H−1H Dipolar Couplings in NMR Spectra of Field Oriented Oligosaccharides

“…Resonances from the weakly oriented soluble molecules remain sharp and survive the COSY transfer. Modified COSY experiments which introduce a coupling evolution delay prior to the t 1 evolution period can take advantage of the different T 2 behavior of the lipid and solute to further suppress lipid background 2 (a) DQF-COSY expansion of anomeric to H2 cross-peaks for residues A, B, and C. (b) DQF-COSY expansion of the same region showing the addition of cross-peaks due to through space dipolar couplings between anomeric and neighboring interresidue protons.…”