Spin-edited 2D HSQC–TOCSY experiments for the measurement of homonuclear and heteronuclear coupling constants: Application to carbohydrates and peptides

Analyses, extensions and comparison of three experimental schemes for measuring (nJCH+DCH)-couplings at natural abundance

“…A significant improvement in terms of resolution was accomplished by the introduction of spin state selectivity [58,59,30,62], which separates multiplet components into two subspectra and therefore reduces the amount of signals in a single spectrum by a factor 2. The a and b-components in these experiments are selected either with spin state selective excitation [58] or via spin state selective coherence transfer [63,59].…”

Investigating Antioxidant Properties of the Diterpenes from Seeds of Phalaris canariensis

“…A Bruker DRX-300 NMR spectrometer, operating at 599.19 MHz for 1 H and 150.86 MHz for l3 C, using the UXNMR software package, was used for NMR experiments; chemical shifts are expressed in δ (ppm) using TMS as an internal standard. DEPT l3 C, ID TOCSY, LH-LH DQF-COSY, and HMBC NMR experiments were carried out using the conventional pulse sequences as described in the literature (Nolis and Parella, 2005). HREIMS were measured on a JEOL HX 110 mass spectrometer (JEOL, Tokyo, Japan).…”

Extending long-range heteronuclear NMR connectivities by HSQMBC-COSY and HSQMBC-TOCSY experiments

“…Then, the resulting in-phase 1 H magnetization is suitable for a subsequent TOCSY transfer, allowing the correlation between protons and protonated carbons belonging to the same J(HH) spin subsystem in a single 2D NMR experiment. Numerous modifications of the basic HSQC-TOCSY pulse scheme have been reported including versions designed for the quantitative measurement of the magnitude and the sign of long-range heteronuclear coupling constants ( n J(CH); n > 1) [4][5][6][7][8][9][10][11][12]. An equivalent HSQC-COSY experiment provides analogous molecular information but the additional J(HH) transfer is often limited to a single neighboring proton step.…”