Reductive 13C-methylation of proteins has been used as an isotope labeling strategy to study protein structure, function, and dynamics by nuclear magnetic resonance (NMR) spectroscopy. However, assigning the resulting 13C-dimethylamine peaks in a 1H-13C NMR spectrum has proved to be difficult, but it is important to expand the scope of the method. The assignment strategy presented here utilizes...

Introduction Acetate is a known glia-specific substrate and has been used to study cerebral metabolism and neurotransmission in both human subjects and animals [1-3]. In particular, intravenously administered 13C-labeldd acetate can be used to label cerebral glutamine and glutamate, allowing glutamate-glutamine interactions to be monitored in vivo using 13C MRS and/or proton-detected 13C MRS [4...

Novel 1D and multidimensional solid-state NMR (SSNMR) methods using very fast magic-angle spinning (VFMAS) (spinning speed > 20 kHz) for performing 13C high-resolution SSNMR of paramagnetic organometallic complexes are discussed. VFMAS removes a majority of 13C-1H and 1H-1H dipolar couplings, which are often difficult to remove by RF pulse techniques in paramagnetic complexes because of large p...

Assessing the biodegradation of organic compounds is a frequent question in environmental science. Here, we present a sensitive, inexpensive, and simple approach to monitor microbial mineralization using reverse stable isotope labeling analysis (RIL) of dissolved inorganic carbon (DIC). The medium for the biodegradation assay contains regular organic compounds and 13C-labeled DIC with 13C atom ...

In the structural analysis of lignins by 13C-NMR, signal overlap limits definitive assignment and accurate inten­ sity measurement. Selective labeling by 13C-enrichment of a specific carbon in lignin enhances its signal intensity in the spectrum. Further enhancement of the specifically labeled carbons can be realized via difference spectra created from the enriched and unenriched samples. Diffe...

The biosynthetic origins of the carbon skeleton in graphenone were verified by feeding the culture of spore-derived mycobionts of the lichen Graphis handelii with sodium [1-13C]-acetate, sodium [1,2-13C2]-acetate, sodium [2-13C]-pyruvate, [1,2,3-13C]-glycerol, [13CH3]-methionine and sodium [1,4-13C2]-succinate.

Photochemically induced dynamic nuclear polarisation (photo-CIDNP) in intact bacterial reaction centres has been observed by 13C-solid state NMR under continuous illumination with white light. Strong intensity enhancement of 13C NMR signals of the aromatic rings allows probing the electronic ground state of the two BChl cofactors of the special pair at the molecular scale with atomic selectivit...

We describe a new experiment for measuring homonuclear-decoupled anisotropic chemical shift patterns in doubly 13C-labeled compounds under magic-angle spinning. The experiment combines a pair of selective and non-selective 180 degrees pulses to suppress the 13C-13C scalar and dipolar interactions. This is combined with the recently developed SUPER technique to recouple the chemical shift anisot...

Two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy has been used to assign 13C spectra of the tricyclic antidepressants imipramine and chlorimipramine . The 2DINADEQUATE method was used to unambiguously assign the aromatic spectral region for the former compound. Errors in previous literature assignments based on 1D methods were corrected. For chlorimipramine the pitfalls of class...

Sir: AR-5 (Mycinamicins) antibiotics, 16-membered ring macrolides, are produced by Micromonospora sp. These novel macrolides are potent antibiotics with unusual activity. Structures of these compounds were independently assigned by us and a group of Japanese workers.',') The assignments of the signals in the 13C NMR spectra have been previously reported". In analogy with the origin of the carbo...