Isotope Labeling

Publication Title: 
Molecular & cellular proteomics: MCP

Calorie restriction (CR) promotes longevity. A prevalent mechanistic hypothesis explaining this effect suggests that protein degradation, including mitochondrial autophagy, is increased with CR, removing damaged proteins and improving cellular fitness. At steady state, increased catabolism must be balanced by increasing mitochondrial biogenesis and protein synthesis, resulting in faster protein replacement rates.

Price, John C.
Khambatta, Cyrus F.
Li, Kelvin W.
Bruss, Matthew D.
Shankaran, Mahalakshmi
Dalidd, Marcy
Floreani, Nicholas A.
Roberts, Lindsay S.
Turner, Scott M.
Holmes, William E.
Hellerstein, Marc K.
Publication Title: 
Metabolic Engineering

A key consideration in metabolic engineering is the determination of fluxes of the metabolites within the cell. This determination provides an unambiguous description of metabolism before and/or after engineering interventions. Here, we present a computational framework that combines a constraint-based modeling framework with isotopic label tracing on a large scale.

Suthers, Patrick F.
Burgard, Anthony P.
Dasika, Madhukar S.
Nowroozi, Farnaz
Van Dien, Stephen
Keasling, Jay D.
Maranas, Costas D.
Publication Title: 
Malaria Journal

BACKGROUND: Semi-synthetic artemisinin derivatives are powerful peroxidic drugs in artemisinin-based combination therapy (ACT) recommended as first-line treatment of Plasmodium falciparum malaria in disease-endemic countries. Studies by Eckstein-Ludwig and co-workers showed both thapsigargin and artemisinin specifically inhibit the sarcoplasmic reticulum Ca²?-ATPase of Plasmodium falciparum (PfATP6). In the present study the type of interaction between thapsigargin and artemisinin derivatives as well as the ozonide OZ277 (RBx11160 or arterolane) was evaluated in parasite cultures.

Abiodun, Oyindamola O.
Brun, Reto
Wittlin, Sergio
Publication Title: 

BACKGROUND: Numerous methods have been reported for the determination of artemether (ARM) and its metabolite dihydroartemisinin (DHA) in plasma. However, stability issues in patient plasma have not received enough attention. RESULTS: An LC-MS/MS method for simultaneous determination of ARM and DHA in human plasma (K3EDTA) turned out to be problematic: ARM and DHA were degraded partially or completely in some patient plasma samples as indicated by the stable isotope-labeled internal standards.

Huang, Liusheng
Olson, Alexander
Gingrich, David
Aweeka, Francesca T.
Publication Title: 
Journal of Agricultural and Food Chemistry

Isoflavones have potential for preventing and treating several chronic health conditions, such as osteoporosis, cardiovascular disease, and cancer. In this study, radiolabeled isoflavones were recovered from kudzu (Pueraria lobata) root cultures after incubation with uniformly labeled (14)C-sucrose in the culture medium for 21 days. Approximately 19% of administered label was recovered in the isoflavone-rich dried extracts of kudzu root cultures (90.2 microCi/g or 3.3 MBq/g extract).

Reppert, Adam
Yousef, Gad G.
Rogers, Randy B.
Lila, Mary Ann
Publication Title: 
The American Journal of Clinical Nutrition

BACKGROUND: The nonsteroidal estrogen equol occurs as diastereoisomers, S-(-)equol and R-(+)equol, both of which have significant biological actions. S-(-)equol, the naturally occurring enantiomer produced by 20-30% of adults consuming soy foods, has selective affinity for estrogen receptor-beta, whereas both enantiomers modulate androgen action. Little is known about the pharmacokinetics of the diastereoisomers, despite current interest in developing equol as a nutraceutical or pharmaceutical agent.

Setchell, Kenneth Dr
Zhao, Xueheng
Jha, Pinky
Heubi, James E.
Brown, Nadine M.
Publication Title: 
Journal of Chromatography. A

A general approach for discovering novel catabolic metabolites from a parent biocompound was developed and validated on the metabolism of gamma-tocopherol in human A549 cell. The method is based on LC-MS analysis of in vitro stable isotope-labeled metabolites and assumes that a parent compound and its metabolites share a common functional group that can be derivatized by well-documented reagents.

Yang, Wen-Chu
Regnier, Fred E.
Jiang, Qing
Adamec, Jiri
Publication Title: 
Clinical Biochemistry

Tracer-based metabolomics is a systems biology tool that combines advances in tracer methodology for physiological studies, high throughput "-omics" technologies and constraint based modeling of metabolic networks. It is different from the commonly known metabolomics or metabonomics in that it is a targeted approach based on a metabolic network model in cells.

Paul Lee, W.-N.
Wahjudi, Paulin N.
Xu, Jun
Go, Vay Liang
Publication Title: 
Journal of Agricultural and Food Chemistry

Isotopically labeled tomato carotenoids, phytoene, phytofluene, and lycopene, are needed for mammalian bioavailability and metabolism research but are currently commercially unavailable. The goals of this work were to establish and screen multiple in vitro tomato cell lines for carotenoid production, test the best producers with or without the bleaching herbicides, norflurazon and 2-(4-chlorophenyl-thio)triethylamine (CPTA), and to use the greatest carotenoid accumulator for in vitro 13C-labeling.

Engelmann, Nancy J.
Campbell, Jessica K.
Rogers, Randy B.
Rupassara, S. Indumathie
Garlick, Peter J.
Lila, Mary Ann
Erdman, John W.
Publication Title: 
Journal of Agricultural and Food Chemistry

Consumption of tomato products has been associated with decreased risks of chronic diseases such as cardiovascular disease and cancer, and therefore the biological functions of tomato carotenoids such as lycopene, phytoene, and phytofluene are being investigated. To study the absorption, distribution, metabolism, and excretion of these carotenoids, a bioengineered Escherichia coli model was evaluated for laboratory-scale production of stable isotope-labeled carotenoids.

Lu, Chi-Hua
Choi, Jin-Ho
Engelmann Moran, Nancy
Jin, Yong-Su
Erdman, John W.


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