Home About us Contact
|
Home About us Contact | ||
|
|
||
Deuterium Incorporation (deuterium + incorporation)
Selected AbstractsInfluence of [2H]-labelled acetic acid as solvent in the synthesis of [2H]-labelled perhexilineJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2010Søren Christian Schou Abstract Preparation of deuterium-labelled perhexiline from an unsaturated analogue was performed via reduction with deuterium gas and PtO2 in acetic acid. Low incorporation was observed when using acetic acid as solvent (most abundant mass peak was M), but when changing the solvent to deuterium-labelled acetic acid, e.g. acetic acid-OD or acetic acid- d4, a higher incorporation was observed (most abundant mass peak was M). Using hydrogen gas instead of deuterium gas with deuterium-labelled acetic acid, high levels of deuterium incorporation were observed (most abundant mass peak was M). An attempt to reduce a precursor with a fully deuterated pyridine to obtain perhexiline with a higher content of deuterium failed. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of adding Crabtree's catalyst to rhodium black in direct hydrogen isotope exchange reactionsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 9 2009Søren Christian Schou Abstract A new catalytic system based on rhodium black using Crabtree's catalyst as an additive for direct hydrogen isotope exchange in aromatic compounds has been investigated. The level of deuterium incorporation can be improved from for example 16 to 93%. The new catalyst mixture tolerates a variety of solvents. Copyright © 2009 John Wiley & Sons, Ltd. [source] An improvement to the synthesis of deuterated meso-tetraphenylporphyrinsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 7 2006Motoko S. Asano Abstract An improved method for the synthesis of deuterated tetraphenylporphyrins (TPPs) is reported. In this method, deuterium labelling at the pyrrole,, -position is increased to more than 95 at%. TPP is the most widely used synthetic porphyrin and high deuterium incorporation is essential for spectroscopic studies and kinetic studies involving relaxation processes. Copyright © 2006 John Wiley & Sons, Ltd. [source] Measurement of pulmonary surfactant disaturated-phosphatidylcholine synthesis in human infants using deuterium incorporation from body waterJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2005Paola E. Cogo Abstract The aim of the study was to determine surfactant palmitate disaturated-phosphatidylcholine (DSPC-PA) synthesis in vivo in humans by the incorporation of deuterium from total body water into DSPC-PA under steady state condition. We studied three newborns and one infant (body weight (BW) 4.6 ± 2.9 kg, gestational age 37.5 ± 2 weeks, age 9 ± 9 days) and four preterm newborns (BW 1.3 ± 0.6 kg, gestational age 30.3 ± 2.5 weeks, postnatal age 8.8 ± 9.2 h). All infants were mechanically ventilated during the study and the four preterm infants received exogenous surfactant at the start of the study. We administered 0.44 g 2H2O/kg BW as a bolus intravenously, followed by 0.0125 g 2H2O/kg BW every 6 h to maintain deuterium enrichment at plateau over 2 days. Urine samples and tracheal aspirates (TA) were obtained prior to dosing and every 6 h thereafter. Isotopic enrichment curves of DSPC-PA from sequential TA and urine deuterium enrichments were analyzed by Gas Chromatography-Isotope Ratio,Mass Spectrometry (GC-IRMS) and normalized for Vienna Standard Mean Ocean Water. Enrichment data were used to measure DSPC-PA fractional synthesis rate (FSR) from the linear portion of the DSPC-PA enrichment rise over time, relative to plateau enrichment of urine deuterium. Secretion time (ST) was defined as the time lag between the start of the study and the appearance of DSPC-PA deuterium enrichment in TA. Data were given as mean ± SD. All study infants reached deuterium-steady state in urine. DSPC-PA FSR was 6.5 ± 2.8%/day (range 2.6,10.2). FSR for infants who did not receive exogenous surfactant was 5.7 ± 3.5%/day (range 2.6,9.9%/day) and 7.3 ± 2.1%/day (range 5.1,10.2%/day) in the preterms, whereas DSPC-PA ST was 10 ± 10 h and 31 ± 10 h respectively. Surfactant DSPC-PA synthesis can be measured in humans by the incorporation of deuterium from body water. This study is a simpler and less invasive method compared to previously published methods on surfactant kinetics by means of stable isotopes. Copyright © 2005 John Wiley & Sons, Ltd. [source] High-resolution H/D exchange studies on the HET-s218,295 prion proteinJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2005Alexis Nazabal Abstract In a search for improved resolution of hydrogen/deuterium (H/D) exchange experiments analyzed by mass spectrometry (HXMS), we evaluated two methodologies for a detailed structural study of solvent accessibility in the case of the HET-s218,295 prion protein. For the first approach, after incubation in the deuterated solvent, aggregated HET-s218,295 was digested with pepsin and the generated peptides were analyzed by nanospray mass spectrometry in an ion trap, with and without collision-induced dissociation (CID). We compared deuterium incorporation in peptides as determined on peptide pseudomolecular ions and on b and y fragments produced by longer peptides under CID conditions. For both b and y fragment ions, an extensive H/D scrambling phenomenon was observed, in contrast with previous studies comparing CID-MS experiments and 1H NMR data. Thus, the spatial resolution of HXMS experiments could not be improved by means of MS/MS data generated by an ion trap mass spectrometer. In a second approach, the incorporation of deuterium was analyzed by MS for 76 peptides of the HET-s218,289 peptide mass fingerprint, and the use of shared boundaries among peptic peptides allowed us to determine deuteration levels of small regions ranging from one to four amino acids. This methodology led to evidence of highly protected regions along the HET-s218,295 sequence. Copyright © 2005 John Wiley & Sons, Ltd. [source] Mass spectrometry techniques for detection of ligand-dependent changes in the conformational flexibility of cellular retinol-binding protein type I localized by hydrogen/deuterium exchangeRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2006M. Careri Hydrogen/deuterium exchange, measured by electrospray ionization with orthogonal quadrupole time-of-flight mass spectrometry (ESI-Q-TOFMS) and by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), was used as a means to probe and map differences in conformational flexibility between the ligand-free and ligand-bound forms of cellular retinol-binding protein type I. Labelled fragments were obtained by digestion of the protein with pepsin. The differences in space-resolved time courses of deuterium incorporation identified regions that exhibit a remarkably higher degree of flexibility in the apo-protein than in the holo-protein. These segments encompass residues that are thought, on the basis of structural homology of the retinol carrier with other members of the intracellular lipid-binding proteins family, to belong to the dynamic portal through which all- trans retinol can access its high-affinity, solvent-shielded, binding site. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||