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Analysis of the chirality of [16O,17O,18O] phosphate esters by 31P nuclear magnetic resonance spectroscopy
A stereospecific method for cyclising D-glucose 6-[16O, 17O,18O]phosphate and adenosine 5′-[ 16O,17O,18O]-phosphate to their conformationally locked six-membered cyclic phosphate diesters has been developed. Using [16O,17O,18O]phosphate esters of known absolute configuration it is shown by 31P n.m.r.…
The effect of 17O and the magnitude of the 18O- isotope shift in 31P nuclear magnetic resonance spectroscopy
The effect of 17O directly bonded to 31P causes marked line broadening of the 31P resonance, but the coupling constant can be detected in favourable systems; the magnitude of the isotope shift caused by 18O directly bonded to 31P depends on the nature of the phosphorus to oxygen bond.
Oxygen chiral phosphate in ribo- and 2'-deoxyribodinucleoside monophosphates by oxidation of phosphite intermediates
Chromatographic separation of the isomers followed by deprotection yielded oxygen chiral dinucleoside monophosphates. The absolute configuration of [10O]UpA has been established. Oxidation of dinucleoside monoDhosDhi.te triesters of ribo and deoxyribonucleosides with iodine-[180]H2O furnished diaste…
On the bromine oxidation of hypophosphate: A 31P(18O) positional isotope investigation
Hypophosphate is oxidised quantitatively by bromine in 18O-labelled water to [18O]pyrophosphate; the 18O label is located exclusively in the non-bridging position. © Royal Society of Chemistry.
A simple method for the configurational analysis of a deoxynucleoside 5′-[16O,18O,S]phosphorothioate
Methylation of 2′-deoxyadenosine 5′-phosphorothioate gives two diastereoisomeric triesters whose configurations can be assigned by 31P n.m.r. spectroscopy by methylation of an asymmetric mixture of the diastereoisomers of 2′-deoxyadenosine 5′-O- methylphosphorothioate after configurational a…
Stereochemical evidence for a phosphorylpyridinium intermediate in the iodine-mediated desulphurisation of a phosphorothioate diester
Desulphurisation of (SP)-5′-O-(2′-deoxyadenosyl)- 3′-O-thymidyl phosphorothioate to 5′-O-(2′-deoxyadenosyl)- 3′-O-thymidyl [18O]phosphate proceeds with epimerisation at phosphorus using iodine in aqueous pyridine but with predominant inversion of configuration in aqueous 2,6-lutidine.
Measurement of the 31P_31P geminal coupling constant in pyrophosphate using the scalar relaxation between 17O and 31P nuclei
Although the scalar relaxation between the quadrupolar nucleus 17O and a phosphorus atom to which it is bonded can cause extreme broadening of the 31P resonance, it does not decouple the 31P nucleus even in a tightly coupled system; consequently the 31p_31p geminal coupling constant in pyrophosphate c…
Oxygen Chiral Phosphate in Undylyl(3'→5')adenosine by Oxidation of a Phosphite Intermediate: Synthesis and Absolute Configuration
Coupling of 2’,5′-silylated uridine and 2’,3′-silylated N6-benzoyladenosine with dichloromethoxyphosphine furnished dinucleoside monophosphite triesters. Oxidation of these intermediates with [17O,18O]H2O and iodine afforded the diastereoisomeric phosphate triesters of fully protected [170, 18O]UpA having…
The stereochemistry of 2-substituted-2-oxo-4,5-diphenyl-1,3,2- dioxaphospholans and the related chiral [16O,17O, 18O]phosphate monoesters
2-Methoxy-2-oxo-4,5-diphenyl-1,3,2-dioxaphospholan prepared by the method of Ukita is shown to be the trans-diastereoisomer; it follows that our [ 16O1,17O, 18O]phosphate monoesters have the (S)-configuration.
A stereochemical investigation of the cyclisation of D-glucose-6[(R)- 16O,17O18O]-phosphate and adenosine- 5′[(R)-16O,17O,18O]phosphate
D-Glucose-6[(R)-16O 17O,18O]phosphate and adenosine-5′[(R)-16O,17O,18O]phosphate were synthesised and converted (by treatment with diphenyl phosphorochloridate, followed by potassium t-butoxide) into the cyclic 4,6-phosphate and 3′5′-phosphate diesters respectively with retention of configuratio…
Synthesis, absolute configuration, and circular dichroism of the enantiomers of fluorosuccinic acid
Diethylaminosulphur trifluoride (DAST) converts (25)- and (2R)-malate esters into the enantiomeric fluorosuccinate esters. (2S,3R)-[3- 2H1]Malate, obtained from fumarate by fumarase-catalysed hydration in deuterium oxide, was used to show that the reaction with DAST occurs stereospecifically with inversion…
Bacteriostatic activity of fluoro-analogues of 5-(2-hydroxyethyl)-4- methylthiazole, a metabolic intermediate in the biosynthesis of thiamine
2-Fluoro-5-(2-hydroxyethyl)-4-methylthiazole and 5-(2-fluoroethyl)-4- methylthiazole have been prepared and the latter converted into a fluoro-analogue of thiamine. All three compounds show bacteriostatic activity against E. coli.
Diversity in striatal synaptic circuits arises from distinct embryonic progenitor pools in the ventral telencephalon.
Synaptic circuits in the brain are precisely organized, but the processes that govern this precision are poorly understood. Here, we explore how distinct embryonic neural progenitor pools in the lateral ganglionic eminence contribute to neuronal diversity and synaptic circuit connectivity in the mouse striatu…
Spread of pathological human Tau from neurons to oligodendrocytes and loss of high-firing pyramidal neurons in aging mice.
Intracellular aggregation of hyperphosphorylated Tau (pTau) in the brain is associated with cognitive and motor impairments, and ultimately neurodegeneration. We investigate how human pTau affects cells and network activity in the hippocampal formation of the THY-Tau22 tauopathy model mic…
Serum apolipoprotein profile of hypertriglyceridemic patients with chronic renal failure on hemodialysis: a comparison with type IV hyperlipoproteinemic patients.
Thirty-three patients with chronic renal failure (CRF) and uremic hypertriglyceridemia (HTG) on hemodialysis were compared with 33 type IV hyperlipoproteinemic patients matched for age, body mass index (BMI), and triglyceride (TG) levels. The two forms of hypertriglyceridemia showed differen…