The greatly improved sensitivity resulting from the use of TROSY during 15N evolution and amide proton acquisition enables the recording of HNCA spectra of large proteins with constant-time 13C alpha evolution. In [13C]-ct-[15N,1H]-TROSY-HNCA experiments with a 2H/13C/15N-labeled 110 kDa protein, 7,8-dihydroneopterin aldolase from Staphylococcus aureus, nearly all correlation peaks seen in the ...

Continuous flow 13C NMR spectroscopy has been used for the first time to monitor the metabolism of a 13C labeled drug in an isolated liver. Continuous and almost immediate information on the metabolite formation could be obtained using 13C labeled phenacetin without alteration of the biological system. The data are consistent with those observed by conventional techniques (HPLC, aliquot 13C NMR...

Arctic landscapes are characterized by a diversity of ecosystems, which differ in plant species composition, litter biochemistry, and biogeochemical cycling rates. Tundra ecosystems differing in plant composition should contain compositionally and functionally distinct microbial communities that differentially transform dissolved organic matter as it moves downslope from dry, upland to wet, low...

The gastrointestinal handling and metabolic disposal of [1-13C]palmitic acid, [1-13C]stearic acid and [1-13C]oleic acid administered within a lipid-casein-glucose-sucrose emulsion were examined in normal healthy women by determining both the amount and nature of the 13C label in stool and label excreted on breath as 13CO2. The greatest excretion of 13C label in stool was in the stearic acid tri...

Previs, Stephen F., Gary W. Cline, and Gerald I. Shulman. A critical evaluation of mass isotopomer distribution analysis of gluconeogenesis in vivo. Am. J. Physiol. 277 (Endocrinol. Metab. 40): E154–E160, 1999.—There are conflicting reports concerning the reliability of mass isotopomer distribution analysis (MIDA) for estimating the contribution of gluconeogenesis to total glucose production (f...

Fatty acid-free albumin has been the standard carrier for intravenous infusion of fatty acids to study in vivo lipid metabolism. However, subjects can have adverse reactions to infusion of albumin. We sought an alternative to albumin as a carrier for intravenous infusion of fatty acids, using the pig as a model. Cyclodextrins are naturally occurring water-soluble molecules that can serve as car...

In the present study, we applied nuclear magnetic resonance (NMR), as well as near-infrared (NIR) spectroscopy, to Jatropha curcas to fulfill two objectives: (1) to qualitatively examine the seeds stored at different conditions, and (2) to monitor the metabolism of J. curcas during its initial growth stage under stable-isotope-labeling condition (until 15 days after seeding). NIR spectra could ...

Glucose metabolism in five healthy subjects fasted for 16 h was measured with a combination of [U-13C]glucose and 2H2O tracers. Phenylbutyric acid was also provided to sample hepatic glutamine for the presence of 13C-isotopomers derived from the incorporation of [U-13C]glucose products into the hepatic Krebs cycle. Glucose production (GP) was quantified by 13C NMR analysis of the monoacetone de...

AIM To examine the gastrointestinal handling and metabolic disposal of emulsified [1-13C]palmitic acid esterified into a triglyceride in nine healthy children and seven patients with cystic fibrosis on enzyme replacement treatment. METHODS After an overnight fast, each child was given 10 mg/kg body weight [1,1,1-13C]tripalmitin with a standardised test meal of low natural 13C abundance. The t...

We present the result of a quantitative analysis of 12C/13C ratios in 26 J-type carbon stars. The 12C/13C ratios are determined from lines of the CN red system around 8000 Å, using the iso-intensity method and line-blanketed model atmospheres. The average of 12C/13C ratios in the 26 stars is 4.7 ± 2.8 (standard deviation). All the stars studied, except for two stars, have 12C/13C ratios smaller...