A comprehensive discussion of HSQC and HMQC pulse sequences

Abstract

ABSTRACT:Much of the progress in NMR applications over the last decade has stemmed from the development of proton-detected, heteronuclear multidimensional spectroscopy. The basic building blocks of the multitude of double and triple resonance experiments available today are the heteronuclear multiple quantum correlation (HMQC) and heteronuclear single quantum correlation (HSQC) experiments. The goal of this article is to provide a comprehensive, pedagogical description of these two pulse sequences, with the aid of product operator formalism. Building from basic principles, constant-time experiments, sensitivity-enhanced techniques and the role of pulsed-field gradients for coherence transfer pathway selection are explained in detail. This article is intended to be used as a primer for students and researchers seeking a firm theoretical understanding of the fundamental tools of modern NMR pulse sequences.

Alzheimer?s Disease: Soluble Oligomeric A?(1?40) Peptide in Membrane Mimic Environment from Solution NMR and Circular Dichroism Studies

“…Homo-nuclear Overhauser enhancement spectroscopy (homo-NOESY), total correlation spectroscopy (TOCSY), heteronuclear single quantum spectroscopy (HSQC) (25) and 15 N filtered 3D NOESY experiments were performed in a DPC (20 mM or 5.5 mM) micelle environment for sequence-specific assignment and structural studies. Homo-NOESY (mixing time 150 ms), TOCSY (mixing time 60 ms), HSQC and 15 N filtered 3D NOESY (mixing time 150 ms) were performed for sequence specific assignments and structural studies.…”

Magnetic resonance spectroscopy (MRS) and its application in Alzheimer's disease

“…Gradients are used extensively for two purposes, either rephasing (selection) (37) or dephasing (elimination) (38) of a particular magnetization transfer pathway (21). Whenever gradients are applied in a particular direction (for simplicity's sake, it is assumed here that gradients are applied along the Z direction), it generates a phase factor associated with the coherence level.…”

“…4). Details of operator formalism are provided in the appendix (21). The rephasing of magnetization is an important application of gradients and it can be explained by analyzing the magnetization at different points in Fig.…”

“…The fundamental basis of MRS is governed by the same principles of nuclear magnetic resonance (NMR) (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). MRS requires a magnetic field and a radio frequency (RF) transmit pulse at a particular resonant frequency to observe the signal of a specific nuclei (e.g., 1 H, 31 P, 13 C etc.)…”

Determination of natural abundance 15N–1H and 13C–1H dipolar couplings of molecules in a strongly orienting media using two‐dimensional inverse experiments

“…In such situations the HMQC experiment is more advantageous. 20 Furthermore, with one type of chemically equivalent rare spin, the analyses of the one-dimensional spectra taken as a cross-section at the chemical shift position in the indirect dimension of 2D HMQC or the projection taken in the F 2 dimension provides all the dipolar couplings. There is no specific advantage in recording 2D spectra for systems having only one chemically equivalent rare spin and one-dimensional 15 …”