- New insight into the pyruvate decarboxylase-catalysed formation of lactaldehyde from H-D exchange experiments: A 'water proof' active site
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Pyruvate decarboxylase from Saccharomyces cerevisiae catalyses the formation of lactaldehyde from sodium glyoxylate and acetaldehyde. By using deuteriated sodium glyoxylate (sodium [2-2H]glyoxylate monohydrate) as a substrate it was verified that the lactaldehyde formed retains the deuterium atom. The implications of the observed result for the enzyme mechanism are discussed in the light of conclusions derived from recent molecular modelling studies.
- Lobell, Mario,Crout, David H. G.
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p. 1577 - 1581
(2007/10/03)
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- Synthesis of (2S)-O-phosphohomoserine and its C-2 deuteriated and C-3 chirally deuteriated isotopomers: Probes for the pyridoxal phosphate-dependent threonine synthase reaction
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A short efficient synthesis of the threonine synthase substrate (2S)-O-phosphohomoserine and its C-2 deuteriated and C-3 chirally deuteriated isotopomers is described. The synthetic route also provides access to (2S)-homoserine and its C-2 deuteriated and C-3 chirally deuteriated isotopomers in high yield. Preliminary deuterium isotope effect determinations performed using the deuteriated (2S)-O-phosphohomoserines and threonine synthase from E. coli indicate that the removal of protons from both C-2 and C-3 is kinetically important.
- Barclay, Fiona,Chrystal, Ewan,Gani, David
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p. 683 - 689
(2007/10/03)
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- ORGANIC CHEMISTRY IN WATER (PART V) NUCLEOPHILIC ADDITION OF WATER-SOLUBLE PHOSPHINES ON ACTIVATED ALKYNES: AN EFFICIENT SYNTHESIS OF NEW VINYLPHOSPHONIUM SALTS AND OF SPECIFICALLY DEUTERATED OLEFINS.
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Triphenylphosphine m-trisulfonate 1 and triphenylphosphine m-monosulfonate 2 react in water with activated alkynes R-CC-A (A = CO2H, CO2R1, COR2, CHO) affording new vinylphosphonium salts or vinylphosphine oxides or alkenes depending on the pH of the aqueous solution and on the nature of the substituent R.The reactions of 1 or 2 with alkynes bearing an electron-acceptor substituent R give rise to the corresponding trans disubstituted olefins.Specifically mono or dideuterated alkenes are thus obtained in good yields by sequential use of H2O-D2O.When R = H or Alkyl, vinylphosphonium salts or vinylphosphine oxides are quantitatively produced respectively in acidic or in neutral solution.
- Larpent, Chantal,Meignan, Gerard,Patin, Henri
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p. 6381 - 6398
(2007/10/02)
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- A Highly Efficient and Large-Scale Synthesis of (2S,3S)-- and (2S,3R)-Aspartic Acids via an Immobilized Aspartase-Containing Microbial Cell System
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This paper describes the preparation and utilization of an immobilized aspartase-containing Escherichia coli system for the large-scale synthesis of (2S,3S)-- and (2S,3R)-aspartic acids from the appropriately labeled fumaric acids in >95percent isolated yield, with >97percent deuterium incorporation at the C-3 center and optically pure at both the C-2 and C-3 centers.
- Lee, Kang-Man,Ramalingam, Kondareddiar,Son, Jong-Keun,Woodard, Ronald W.
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p. 3195 - 3198
(2007/10/02)
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- A NEW SYNTHESIS OF VINYLPHOSPHONIUM SALTS. APPLICATION FOR DEUTERIUM LABELING(1)
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Nucleophilic additions of water-soluble phosphines on γ-alcynic acids afford new vinylphosphonium salts which are easily transformed into specifically deuteriated olefins or phosphine oxides by using sequentially H2O or D2O.
- Larpent, Chantal,Patin, Henri
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p. 4577 - 4580
(2007/10/02)
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- Stereochemistry of the Ethanolamine Ammonia Lyase Reaction with Stereospecifically Labeled 1>-2-Aminoethanol
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The antipodes of 1>-2-aminoethanol (10) have been synthesized from (S)-1>benzyl alcohol and separately subjected to the action of ethanolamine ammonia lyase in the presence of alcohol dehydrogenase, in order to determine whether the migration of a hydrogen atom from C-1 to C-2 during acetaldehyde formation is stereospecific. (R)-10 reacts 4 times as fast as (S)-10, the isotope effect showing that the pro-S hydrogen migrates preferentially in each case. 1H and 13C NMR spectra of the ethanol formed show that (R)-10 leads to CH3CHDOH while (S)-10 affords DCH2CH2OH, confirming the stereoselectivity of hydrogen transfer.
- Yan, Shou-Jen,McKinnie, B. Gary,Abacherli, Claudio,Hill, Richard K.,Babior, Bernard M.
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p. 2961 - 2964
(2007/10/02)
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- Synthesis of L-Glutamic Acid Labelled Stereospecifically at C-3 with Deuterium and Non-stereospecifically at C-4 with Tritium
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(2S,3S)-1>-, (2S,3R)-2>-, (2S,3S,4RS)-1,4-3H1>-, and (2S,3R,4RS)-2,4-3H1>-Glutamic acid have been synthesised from the corresponding labelled aspartic acids.The route involves a step where Wolff rearrangement occurs with retention of stereochemistry at a primary migrating chiral centre.The stereochemistry at C-3 of the glutamic acids has been verified by degradation to the corresponding stereospecifically labelled 1>succinic acids.
- Field, Steven J.,Young, Douglas W.
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p. 2387 - 2392
(2007/10/02)
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