A previous 13C NMR technique (Malloy, C. R., Sherry, A.D., and Jeffrey, F.M.H. (1987) FEBS Lett. 212, 58-62) for measuring the relative flux of molecules through the oxidative versus anaplerotic pathways involving the citric acid cycle of the rat heart has been extended to include a complete analysis of the entire glutamate 13C spectrum. Although still simple in practice, this more sophisticate...

BACKGROUND AND AIMS The 13C-Hiolein breath test (98% [U-13C] labelled long chain triglyceride mixture (highly labelled triolein) was evaluated as a non-invasive, non-radioactive test for exocrine pancreatic insufficiency. Accuracy and clinical validity were examined with reference to both the secretin pancreozymin test and faecal fat analysis. METHODS A secretin pancreozymin test and faecal f...

The selective and extensive 13C labeling of mostly hydrophobic amino acid residues in a 25 kDa membrane protein, the colicin Ia channel domain, is reported. The novel 13C labeling approach takes advantage of the amino acid biosynthetic pathways in bacteria and suppresses the synthesis of the amino acid products of the citric acid cycle. The selectivity and extensiveness of labeling significantl...

Abies alba (European silver fir) was used to investigate possible effects of simulated browsing on C allocation belowground by 13CO2 pulse-labelling at spring, summer or autumn, and by harvesting the trees at the same time point of the labelling or at a later season for biomass and for 13C-allocation into the fine-root system. Before budburst in spring, the leader shoots and 50% of all lateral ...

We describe a new method for exciting triple-quantum coherences in 13C-labelled powder samples under MAS. The proposed method combines selective double-quantum excitation with rotational resonance and frequency-selective composite pulses. The spin dynamics of this new method are described theoretically. Numerical calculations of the spin dynamics are compared to experimental results on fully 13...

Efficient syntheses of pyrimidine and purine nucleosides and nucleotides with selective 13C enrichment in the base moieties are described. Uridine and cytidine are labeled at position C6 and adenosine and guanosine are labeled at position C8. The selectively labeled nucleosides were converted to nucleoside triphosphates and used with in vitro transcription to synthesize labeled RNA. Isotope-edi...

We show how high-resolution magic angle-spinning NMR spectroscopy can be used to characterize 13C-labeled saccharides that have been prepared using solid-phase synthesis techniques while they are still bound to a solid-support resin. With the use of 13C-labeled glucose as the starting material, we have successfully synthesized mono-, di- and trisaccharides with uniform 13C labeling of the sacch...

We investigated the effect of deformation of natural rubbers (NR) resulting from the high centrifugal pressure of fast magicangle spinning (MAS) on 13C NMR spectra. The solid state 13C MAS NMR spectrum with high-power 1H dipolar decoupling (DD) of NR presents liquid-like, very narrow signals (full width at half height, FWHH, is less than 10 Hz). However, the static state 13C DD NMR spectrum of ...

Alfalfa was labeled in the field with 99 atom % 13CO2 and cut either the same day (C1) or 30 d after labeling (C30). The C1 alfalfa contained 84% of the 13C label in cell contents, whereas C30 alfalfa contained 47% of the 13C label in cell contents. In two separate trials, C1 and C30 alfalfa were dosed to two or four Suffolk ewes fed natural abundance alfalfa diets. Carbon isotope ratios (13C/1...

The 13C content of microbial products are controlled by many factors, including the 13C content of the growth substrate, growth rate, the flux of carbon through various parts of the biochemical network, and the isotopic fractionation imposed by the enzymes of that network. We analyzed the 13C content of products of the methanogen Methanosarcina barkeri and found that fractionation varied strong...