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Topic: Isotopomers

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	isotsep (Site not responding. Last check: 2007-10-11)
		The dye laser, which is pumped by a copper-vapour laser, photoionizes the U atoms selectively according to their mass, and the ions are deflected by the electric field applied between the plates.
		Isotopomers may be separated by making use of their selective absorption of infrared photons followed by photodissociation with an ultraviolet photon.
		In an alternative scheme for separating isotopomers, multiphoton absorption of infrared photons is used to reach the dissociation limit of a ground electronic state.
	www.raunvis.hi.is /~agust/isotsep.htm (128 words)

	Isotopomers - Wikipedia, the free encyclopedia
		Isotopomers (isotopic isomers) are isomers having the same number of each isotopic atom but differing in their positions.
		An isotopomer should not be confused with an isotopologue.
		This page was last modified 11:31, 4 November 2005.
	en.wikipedia.org /wiki/Isotopomer (63 words)

	BioMed Central \| Full text \| Integration of enzyme kinetic models and isotopomer distribution analysis for studies of ...
		The comprehensive analysis of mass isotopomer data obtained by MS also demands that all possible individual isotopomers are computed, because every mass isotopomer is the sum of several individual isotopomer concentrations and each component of the sum could be produced in the different way.
		This algorithm of isotopomer mapping matrices, evolved from the earlier approach of atom mapping matrices [2,26], allowed to construct and solve automatically hundreds of equations that describe all isotopomers transformation according to the specific reaction mechanisms.
		Assuming that all isotopomers have the equal affinity, the rate of reaction between pair of isotopomers is proportional to their concentrations, while the sum of reaction rates for all isotopomers gives the global metabolic flux calculated also at the previous, kinetic, step.
	www.biomedcentral.com /1471-2202/7/S1/S7 (7394 words)

	Temporal and latitudinal distributions of stratospheric N2O isotopomers
		O isotopomers were observed in the stratosphere over Japan (39°N, 142°E), Sweden (68°N, 20°E), and Antarctica (69°N, 40°E) during the period between 1990 and 2001.
		We found that in the higher-altitude region (1) fractionation of the isotopomers is mainly determined by photolysis, but is also affected by physical processes, (2) subsidence of air masses in the winter polar vortex induces the intrusion of an upper stratospheric air mass depleted in N
		At lower altitudes, isotopomer ratios are determined by photolysis, photo-oxidation, and the mixing of air masses within the stratosphere or between the stratosphere and the troposphere.
	www.agu.org /pubs/crossref/2004/2003JD004316.shtml (532 words)

	Isotopomery Project (Site not responding. Last check: 2007-10-11)
		The crux of the matter is that the positional isotopic mixture of a compound in a sample is dependent on the raw materials and the transformations they have undergone, i.e., the history of the sample.
		Isotopomers are compounds of the same chemical composition and structure, but with different isotopes of their constituent chemical elements in the same positions.
		For more complex compounds the difference between the number of unknowns (proportions of specific isotopomers in the mixture) and the number of equations (relative intensity of lines in the cluster) grows very fast.
	isotopomery.com (316 words)

	Simulationstechnik: 13C MFA (Site not responding. Last check: 2007-10-11)
		C MFA in the newer literature is that of an isotopomer of a given metabolite.
		The term isotopomer is a combination of the terms isotope and isomer and it means one of the different labeling states in which a particular metabolite can be encountered (Figure 3).
		The isotopomer distribution of a metabolite with n carbon atoms is characterised by the percentage of each isotopomer within the metabolite pool, i.e.
	www.simtec.mb.uni-siegen.de /index.php?id=450 (1875 words)

	Metabolic Engineering Work (Site not responding. Last check: 2007-10-11)
		An isotopomer is a molecule that is labled with a
		Isotopomers, however are not enough to solve the system (Wiechert et al.
		To convert isotopomers to cumomers I have written a program that takes a vector of counting numbers representing the number of carbons in each metabolite and returns a square matrix.
	www.owlnet.rice.edu /~akoller/meteng.html (239 words)

	Isotopomers (Site not responding. Last check: 2007-10-11)
		Isotopomers (isotopic isomers) are isomers having the same number of each Isotopic atom but differing in their positions.
		For example, CH and CH D are a pair of constitutional isotopomers.
		An isotopomer should not be confused with an Isotopologue.
	www.ufaqs.com /wiki/en/is/Isotopomers.htm (57 words)

	Dr. Jäger’s Group Homepage - Ohio 2001 - Jennifer van Wijngarden’s Talk
		The other isotopomers are asymmetric tops and due to the reduced symmetry, all rotational levels are present in these complexes.
		For the deuterium containing isotopomers, each rotational transition is split by the inversion motion of ammonia within the complex.
		N nuclear quadrupole coupling constants, were fit for each isotopomer and used to derive structural and dynamical information for the Ar and Ne van der Waals complexes.
	www.chem.ualberta.ca /~jaeger/conferences/ohio_2001_c.htm (188 words)

	A Mass Isotopomer Study of Urea and Glutamine Synthesis from 15N-labeled Ammonia in the Perfused Rat Liver -- Brosnan ...
		Cl, and the isotopomers of urea and of glutamine produced were determined by gas chromatography-mass spectrometry methodology.
		N enrichment of citrulline and aspartate in the perfusate were used as proxies for that in the mitochondrial ammonia and cytoplasmic aspartate pools we could accurately predict the relative proportion of the three isotopomers.
		Theoretical relative abundance of the nitrogen isotopomers of urea.
	www.jbc.org /cgi/content/full/271/27/16199 (6695 words)

	ARS \| Publication request: Impaired Synthesis of Docosahexaenoic Acid (Dha) in Patients with X-Linked Retinitis ...
		Mean accumulations of m+18 isotopomers of 18:3n-3, 18:4n-3, and 20:4n-3 was 46% % 26% and 49% higher, respectively, in patients with XLRP than in controls.
		In contrast, mean accumulation of m+18 isotopomers of 20:5n-3, 22:5n-3 and 22:6n-3 in patients with XLRP was 69%, 68% and 46%, respectively, of that in controls.
		Despite interindividual variation in rates of endogenous conversion of 18:3n-3 to 22:6n-3 in both groups, these data are consistent with a lower rate of Delta5 desaturation in patients with XLRP and/or some combination of a lower rate of elongatio of 22:5n-3 to 24:5n-3, Delta6 desaturation of 24:5n-3 or beta-oxidation of 24:6n-3.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=112895 (386 words)

	JST Developed New Measuring Method of Isotopomers of a Global Warming Gas and Succeeded in its Observation
		Japan Science and Technology Corporation (JST) developed a new technique to analyze the difference between isotopomers of N２O which is one of global warming gases, as a part of the research in its core research for evolutional science and technology (CREST) project, and succeeded to observe practically N２O molecules in the atmosphere.
		This achievement was made by a group led by Professor Naohiro Yoshida of the Graduate School of Tokyo Institute of Technology, as part of the research theme "Isotopomer Analysis of Environmental Materials for their Source Derimination" in the research area "Social System for Better Environmental Performance" of the CREST project.
		As for substances in the environment, there exist a great number of isotopomers which have the same chemical formula but have slighty different properties due to isotope differences, their positions and combinations.
	www.mext.go.jp /english/news/2000/05/g000506.htm (337 words)

	APStracts 5:0016E, 1998. (Site not responding. Last check: 2007-10-11)
		The distribution of these isotopomers was used to estimate parameters of the PPP using the model of Katz and Rognstad.
		Mass and position isotopomers of ribose, and lactate and palmitate (products from triose phosphate) from human hepatoma cells (Hep G2) incubated with 30% enriched [1, 2-13C2]-glucose were determined using GC/MS.
		The observed ribose isotopomer distribution was best matched with those provided from simulation by substituting 0.032 for transketolase (TK) and 0.85 for transaldolase (TA) activity relative to glucose uptake into the model of Katz and Rognstad.
	www.uth.tmc.edu /apstracts/1998/endo/January/16E.html (353 words)

	On the possible interconversion between pairs of deuterated isotopomers of methanol, its ion, and its protonated ion in ... (Site not responding. Last check: 2007-10-11)
		Deuterated isotopomers of methanol have been detected both in hot cores and in the protostellar source IRAS 16293-2422.
		It is currently thought that these species are formed on cold grain surfaces in a previous era by the hydrogenation and deuteration of CO via reactions with atomic H and D. Methanol and its singly, doubly, and multi-deuterated isotopomers then evaporate or are sputtered into the gas as star formation occurs.
		In studying the post-evaporative gas-phase chemistry of these isotopomers, it is important to know if pairs of isotopomers with D atoms in different places (e.g.
	www.edpsciences.org /articles/aa/abs/2004/27/aa0762/aa0762.html (270 words)

	Starch Biosynthesis and Intermediary Metabolism in Maize Kernels. Quantitative Analysis of Metabolite Flux by Nuclear ...
		C-labeling (isotopomers g and h) is indicated by dots.
		A through C, simulated signals of isotopomers a, d, and e, respectively; D, sum of the simulated signals scaled according to the molar fractions of isotopomers in the experiment with [U- ]Glc (compare with Table III); E, signal of the biosynthetic sample from the experiment with experiment with [U- ]Glc.
		A through C, Simulated signals of isotopomers a, f, and d; D, sum of the simulated signals scaled according to the molar fractions of isotopomers in the experiment with [U- ]Glc (compare with Table III); E, signal of the biosynthetic sample from the experiment with experiment with [U- ]Glc.
	www.plantphysiol.org /cgi/content/full/130/4/1717 (4232 words)

	Microbial Cell Factories \| Full text \| Fluxome analysis using GC-MS (Site not responding. Last check: 2007-10-11)
		Similarly mass isotopomer distributions of other metabolites give access to various other flux parameters, such as dual pathways in amino acid biosynthesis [64], bidirectional fluxes around the pyruvate node [64] or parallel pathways in different cellular compartments [18] and different flux ratios [24].
		Also other protocols for resolution of positional isotopomer pools are rather laborious and include various steps for purification and chemical or enzymatic conversion of the analytes [35,49,68,69] which impedes the broad and routine use of such techniques.
		It should be noticed that the resolution of single positional isotopomer pools not necessarily leads to an increase in information for flux quantification [67,70], but in selected cases single isotopomer pools might be required to calculate all fluxes of interest.
	www.microbialcellfactories.com /content/6/1/6 (7562 words)

	ISI 2003 Symposium (Site not responding. Last check: 2007-10-11)
		The study of isotopomers has an increasing number of applications in various scientific fields ranging from environmental studies (including global warming) to life sciences relevant to many areas of interests for human activities (Agriculture, food authentication, pharmacology, health care etc…).
		The purpose of the Symposium is to look into the latest scientific achievements in the measurement and analysis of isotopomers, from the studies of environmental changes to further applications in environmental and life sciences including food authenticity and biomedical research.
		Observations of isotopomer variations in the atmosphere, the oceans, the terrestrial environment and the biosphere.
	www.jrc.cec.eu.int /pce/isi2003/isi2003.html (1285 words)

	Auxin Biosynthesis in Maize Kernels -- Glawischnig et al. 123 (3): 1109 -- PLANT PHYSIOLOGY
		The isotopomer composition of Trp, Leu, Tyr, and His was determined (Table II; Fig.
		The according isotopomer formula and the definition of the abbreviation is given in Table II.
		C labeling is shown by bold lines and the normalized abundance of the isotopomer is given (Tables II and III).
	www.plantphysiol.org /cgi/content/full/123/3/1109 (5050 words)

	First Principles Computation of Thermochemical Properties Beyond the Harmonic Approximation. II. Application to the ...
		For this quantitative agreement with experiment, both f functions and core correlation seem to be prerequisite.
		Using a hybrid analytic/direct summation method recently developed by the present authors, the thermodynamic functions gef(T), hef(T), S0, and Cp are computed including exact accounts for anharmonicity and rovibrational coupling, and very good analytical approximations to centrifugal distortion and quantum rotation effects.
		Thermodynamic tables in JANAF style from 100-3000 K, as well as a full set of rovibrational spectroscopic constants, are presented for NH2 and all important isotopomers.
	library.wolfram.com /infocenter/Articles/2510 (199 words)

	ARS \| Publication request: Determination of 13c-Labeled and Endogenous Beta-Carotene, Lutein, and Vitamin a in Human ...
		The determination of the retinol isotopomers from plasma was carried out using labeled internal standards by GC-MS with NCI detection.
		The total plasma concentrations of all trans-lutein was quantified by HPLC analysis with UV detection using beta- apo-8'-carotenal as an internal standard and the ratio of the 13C:12C isotopomers of lutein were determined by PB-MS.
		The retinol isotopomers were collected from HPLC fractions of the plasma extract and then analyzed as the trimethylsilyl ethers by GC-MS.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=123225&pf=1 (383 words)

	Mass isotopomer distribution analysis at eight years: theoretical, analytic, and experimental considerations -- ...
		Mass isotopomer distribution analysis (MIDA) is a technique for measuring the synthesis of biological polymers.
		A histogram of the abundances of the mass isotopomers of a molecule.
		C: use of high-mass isotopomer analysis to identify inhomogeneity in the precursor pool, in this case, an isotopic gradient in the precursor pool.
	ajpendo.physiology.org /cgi/content/full/276/6/E1146 (8592 words)

	Second Northeast Microwave Symposium (Site not responding. Last check: 2007-10-11)
		Using the isotopomers yields the unambiguous position of the argon that could not be determined from the parent complex alone.
		Large amplitude cross ring argon motion causes the two carbons bonded to the sulfur to be equivalent.
		High resolution gas phase spectroscopic studies of organoselenium compounds are complicated by the presence of six naturally occurring selenium isotopomers.
	chemistry.uconn.edu /calendar/3nemw.html (1385 words)

	Computer Simulation of Metabolism - Center for Plant Environmental Stress Physiology - Department of Horticulture and ...
		The time-courses of changes in relative abundance and absolute amounts of isotopomers of citrate, ketoglutarate, succinate, malate and oxaloacetate are simulated in the following 5 figures.
		Each possible isotopomer of citrate produced during either the "pulse" or the "chase" (including the unlabeled species C) is enumerated.
		The pool size of each citrate isotopomer can initially expand due to synthesis during each iteration (z), depending upon the probability of utilizing unlabeled acetyl-CoA (PuAc) or acetyl-CoA labeled in the carbon 2 position (PuA2) [where PuAc + PuAc2 = 1], the probability of utilizing the various isotopomers of oxaloacetate (e.g.
	www.hort.purdue.edu /cfpesp/models/mo00013.htm (2094 words)

	This is Preses#7 abstract:Vacuum ultraviolet photochemistry of CH₄ and isotopomers. II. Product channel ... (Site not responding. Last check: 2007-10-11)
		This is Preses#7 abstract:Vacuum ultraviolet photochemistry of CH and isotopomers.
		A complete set of quantum yields for the different photodissociation channels of each isotopomer is obtained by combining the two sets of data.
		Previously it was found that H atoms are almost four times more likely than D atoms to be ejected; now it is found that hydrogen molecule photofragments are much richer in H atoms than in D. Overall, the heavier D atoms are more likely than the H atoms to remain attached to the carbon atom.
	www.chemistry.bnl.gov /gpmd/old-pages/PRESAB7.HTML (182 words)

	Protein kinetics determined in vivo with a multiple-tracer, single-sample protocol: application to lactase synthesis -- ...
		B: theoretical tracer-to-tracee ratios with time of a hypothetical protein calculated from tracer-to-tracee ratio of each phenylalanine isotopomer in the sample at the end of the infusion.
		The data on the ion abundances of the respective amino acid isotopomers were converted to tracer-to-tracee ratios by the matrix
		Determination of multiply labeled serine and glycine isotopomers in human plasma by isotope dilution negative-ion chemical ionization mass spectrometry.
	ajpgi.physiology.org /cgi/content/full/274/3/G591 (4373 words)

	The resonance enhanced multiphoton ionisation spectroscopy of ammonia isotopomers NH3, NH2D, NHD2 and ND3 (Site not responding. Last check: 2007-10-11)
		The resonance enhanced multiphoton ionisation spectroscopy of ammonia isotopomers NH and ND Nolde, K.-M. Weitzel and C.M. Western.
		The C' Rydberg states of the ammonia isotopomers NH and ND have been investigated by (2 + 1) resonance enhanced multiphoton ionisation spectroscopy.
		The current work provides the basis for future studies of the chemical reactions of the mixed isotopomers of ammonia ions formed by the REMPI technique.
	www.chm.bris.ac.uk /pt/western/a/nh2d.htm (106 words)

	Mass Spectrometry (Site not responding. Last check: 2007-10-11)
		Note that molecular weight, or more correctly formula weight (the mass in grams of one mole of compound), is actually a weighted average of the molecular masses of all the isotopic variants of a given molecule.
		For small organic compounds a mass spectrometer can resolve the individual "isotopomers" and the mass of the major one (the so-called mono-isotopic mass) is very close to the formula weight of the compound.
		However for big molecules, isotopomers are not generally resolved and what one measures is the average molecular mass; this is always larger than the monoisotopic mass by at least a few mass units.
	www.brsl.ku.edu /bioms2.htm (798 words)

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