Nucleolar 28 S, 35 S, and 45 S RNA's were isolated from normal rat liver, Novikoff hepatoma ascites cells, and Morris hepatoma 9618A after short (60 min) and long (6 hr) labeling with orthophosphate-32p. After purification by sucrose density sedimentation, the 32p nucleotide composition of these RNA's was determined. The RNA was hydrolyzed to oligonucleotides with pancreatic ribonuclease. The d...

The dynamics of label propagation in a stationary metabolic network during an isotope labeling experiment can provide highly valuable information on the network topology, metabolic fluxes, and on the size of metabolite pools. However, major issues, both in the experimental set-up and in the accompanying numerical methods currently limit the application of this approach. Here, we propose a metho...

We report the mechanistic investigation of catalytic H2 evolution from formic acid in water using a formate-bridged dinuclear Ru complex as a formate hydrogen lyase model. The mechanistic study is based on isotope-labeling experiments involving hydrogen isotope exchange reaction.

The cell’s fate is largely governed by the dynamics of cellular events, brought about by the interplay of various proteins, in which post-translational modifications (PTMs) play a key role. Therefore, a better understanding of post-translational modification is of utmost importance to a biochemist. Over the years much work in this regard has been achieved through mass spectrometry, however, the...

MS1 full scan based quantification is one of the most popular approaches for large-scale proteome quantification. Typically only three different samples can be differentially labeled and quantified in a single experiment. Here we present a two stages stable isotope labeling strategy which allows six different protein samples (six-plex) to be reliably labeled and simultaneously quantified at MS1...

High field deuterium NMR spectra have been recorded for various horseradish peroxidase complexes reconstituted with hemins possessing specific 2H labels. The line width of the 2H NMR signals of deuteroheme reconstituted-horseradish peroxidase (HRP) and its cyano complex for the immobilized skeletal 2-2H and 4-2H labels yield the overall protein rotational correlation time (22 ms at 55 degrees C...

Abstract. There is growing interest in developing spatially resolved methane (CH4) isotopic source signatures to aid geographic attribution of CH4 emissions. hydrogen isotope measurements (?2H–CH4) have the potential be a powerful tool for differentiation emissions from freshwater environments, as well other microbial sources. This because ?2H–CH4 values are partially dependent on ?2H environme...

High confidence definition of protein interactions is an important objective toward the understanding of biological systems. Isotope labeling in combination with affinity-based isolation of protein complexes has increased in accuracy and reproducibility, yet, larger organisms--including humans--are hardly accessible to metabolic labeling and thus, a major limitation has been its restriction to ...

Stable isotope dilution mass spectrometry (MS) represents the gold standard for quantification of endogenously formed cellular metabolites. Although coenzyme A (CoA) and acyl-CoA thioester derivatives are central players in numerous metabolic pathways, the lack of a commercially available isotopically labeled CoA limits the development of rigorous MS-based methods. In this study, we adapted sta...

Abstract The functionalization of carbon dioxide (CO2) as a C1 building block has attracted enormous attention. Carboxylation reactions, in particular, are major interest for applications isotope labeling. Due to the inexpensive nature CO2, information about its stoichiometric use is generally unavailable literature. Because rarity and limited availability CO2 isotopomers, this parameter concer...