- NOVEL COELENTERAZINE SUBSTRATES AND METHODS OF USE
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An isolated polynucleotide encoding a modified luciferase polypeptide and novel coelenterazine- based substrates. The OgLuc variant polypeptide has at least 60% amino acid sequence identity to SEQ ID NO: 1 and at least one amino acid substitution at a position corresponding to an amino acid in SEQ ID NO: 1. The OgLuc variant polypeptide has at least one of enhanced luminescence, enhanced signal stability, and enhanced protein stability relative to the corresponding polypeptide of the wild-type Oplophorus luciferase.
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Page/Page column 59
(2012/05/20)
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- Process for the preparation of enantiomerically enriched compounds
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1. Process for the preparation of enantiomerically enriched amino aldehydes and amino alcohols, wherein a corresponding enantiomerically enriched amino nitrile is subjected to hydrogenation in the presence of hydrogen, a hydrogenation catalyst, preferably a Pd-catalyst and a mineral acid. For the preparation of an amino aldehyde hydrogen preferably is present at a hydrogen-pressure between 0.1 and 2 MPa, in particular between 0.5 and 1 MPa. The amino aldehyde preferably is isolated in the form of a chemically and configurationally stable derivative. For the preparation of an amino alcohol, preferably at least during part of the hydrogenation hydrogen is present at a hydrogen-pressure between 2 and 10 MPa, in particular between 4 and 6 MPa. In a preferred embodiment the hydrogen-pressure initially is between 0,5 and 2 MPa and subsequently, after most of the nitrile starting material is converted, the hydrogen pressure is increased to a value between 2 and 10 MPa. The enantiomerically enriched nitrile starting material may a.o. be prepared by enzymatic resolution, classical resolution, resolution via preferential crystallization, diastereomeric synthesis, catalytic asymmetric synthesis or dehydratation of amino acid amides.
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Page/Page column 4
(2010/11/29)
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- Synthesis and tautomeric equilibrium of 6-amino-5-benzyl-3-methylpyrazin- 2-one. An acceptor-donor-donor nucleoside base analog
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6-Aminopyrazin-2-one, when incorporated as pyrimidine base analog into an oligonucleotide, might participate in a nonstandard base pair that retains a Watson-Crick geometry but is joined by a nonstandard hydrogen bonding pattern. Such base pairs can, at least in principle, be recognized independently in duplex nucleic acids. To explore the tautomeric properties that govern hydrogen bonding of this heterocycle, 6-amino-5-benzyl-3- methylpyrazin-2-one was synthesized. The equilibrium constant for the interconversion of the keto and hydroxyl tautomeric forms was estimated by comparing its ultraviolet spectrum with those of N- and O-methyl derivatives in water, methanol, ethanol, dioxane, and water-dioxane mixtures. A plot of the logarithm of the tautomeric equilibrium constant versus Dimroth's microscopic dielectric constant (E(T)(30)) was linear. On the basis of an extrapolation of this relationship to the microscopic dielectric of water, 6- amino-5-benzyl-3-methylpyrazin-2-one is expected to favor at equilibrium the keto form over the hydroxyl form by a factor of ca. 2000 under conditions where DNA and RNA polymerases operate. This is substantially better than the tautomeric ratio observed with isoguanosine, where the minor form has been observed to create tautomeric ambiguity with some polymerase systems.
- Voegel,Von Krosigk,Benner
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p. 7542 - 7547
(2007/10/02)
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- Heterocycles as Masked Diamide/Dipeptide Equivalents. Formation and Reactions of Substituted 5-(Acylamino)oxazoles as Intermediates en route to the Cyclopeptide Alkaloids
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A variety of novel 2,4-dialkyl-5-(acylamino)oxazoles have been prepared by using either amide nitriles or diamides/dipeptides as starting materials.Ring closure calls for the use of trifluoroacetic acid/trifluoroacetic acid anhydride or an acid halide in
- Lipshutz, Bruce H.,Hungate, Randall W.,NcCarthy, Keith E.
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p. 7703 - 7713
(2007/10/02)
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