Two‐dimensional spectra of intact tissue: Homonuclear Hartmann‐Hahn spectroscopy provides increased sensitivity and information content as compared to COSY

Abstract

Hartmann-Hahn (HOHAHA) spectroscopy led to good definition of proton spin systems of metabolites such as lactate, (phospho) creatine, and carnosine from a 3-g sample of excised frog gastrocnemius muscle in a 17-min experiment. The sign of the HOHAHA cross-peak intensity appears to provide additional information about interactions between metabolites and their protein binding sites.

Molecular dynamics and information on possible sites of interaction of intramyocellular metabolites in vivo from resolved dipolar couplings in localized 1H NMR spectra

“…3). Alonso et al [13] observed a connectivity between these two subgroups in 2D HOHAHA experiments on intact frog m. gastrocnemius, which proves additionally that both subgroups are restricted in mobility. The experiments on human calf muscle demonstrate that the interaction of the protons within each group is the dominant one owing to the strong spatial dependence of the direct spin-spin coupling.…”

“…Regarding the cause of the observed residual dipolar couplings of intramyocellular metabolites, the intrinsic muscle structure must play a crucial role as demonstrated in HOHAHA experiments [13] where negative ROE cross peaks indicating temporal binding of Cs and (P)Cr could only be observed in intact tissue samples and not in muscle tissue extracts and model solutions. Constraints of the molecules between the highly ordered actin-myosin chains or attachment to macromolecules (which could themselves be ordered within the cells) were discussed first [6].…”

“…This effect would slow down chemical exchange making one extra proton detectable. In previous studies [12,13], an additional signal component at d % 8 ppm was indeed identified, but could not be assigned unambiguously to an amide group. To clarify this point, 1 H NMR spectra of N-acetyl-L L-aspartate (NAA) and L L-histidine (His) in aqueous solutions were analysed.…”

In vivo 2D magnetic resonance spectroscopy of small animals

“…There have been several studies in frogs (gastrocnemius biopsies observed with DQF-COSY [57] or with HOHA-HA (HOmonuclear HArtmann HAhn spectroscopy) [47]) sequences and rats (orientation-dependant dipolar coupling in lactate resonance in biopsy muscle studied by DQF and J-resolved 1 H NMR [132]). However, most of these in vitro 2D MRS studies have been performed in mice.…”

“…Total correlation spectroscopy (TOCSY) [45,46] has been used to study muscle lipids [47,48]. This sequence provides all the correlations in a coupling network, resulting in a more characteristic fingerprint of the molecule.…”