- Mimics of Transaminase Enzymes
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Pyridoxamine has been attached to the primary side and to the secondary side of β-cyclodextrin; the resulting compounds convert α-keto acids to amino acids with substrate selectivity and some stereoselectivity.Pyridoxamine has also been attached to a synthetic macrocycle; the attached binding group showed substrate selectivity.Chains carrying catalytic basic groups have been attached to pyridoxamine; appropriate systems catalyze the prototropic rearrangement characteristic of transamination.A catalyzed HCl elimination involving chloropyruvic acid was observed.A tetrahydroquinoline system related to pyridoxamine was synthesized to permit the stereochemically defined placement of a basis catalytic group.This converted keto acids to amino acids with good stereoselectivity for the formation of optically active products.
- Breslow, R.,Czarnik, A. W.,Lauer, M.,Leppkes, R.,Winkler, J.,Zimmerman, S.
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p. 1969 - 1979
(2007/10/02)
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- Kinetic study and analytical application of the hexadecyltrimethylammonium bromide-catalyzed reaction of 1-fluoro-2,4-dinitrobenzene with amines
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Arylation of amines by reaction with 1-fluoro-2,4-dinitrobenzene is catalyzed by micelles of cetrimonium bromide. This catalysis has been exploited to reduce the analysis time in the spectrophotometric determination of amines as their dinitrophenyl derivatives. The kinetics of the catalysis were studied for the five amines: alanine, phenylalanine, aniline, 4-methylaniline, and 4-methoxyaniline. The dependence of rate constant on surfactant concentration can be quantitatively accounted for by Berezin's model, in which uptake of the amine and the 1-fluoro-2,4-dinitrobenzene by the micelle is described as a partitioning phenomenon for both species. An alternative model is developed in which one reactant partitions into the micellar phase and the other binds to the micelle with 1:1 stoichiometry; the two models are formally equivalent. Intrinsic catalytic rate constants and binding constants were evaluated. About one-third to one-half of the maximum observed micellar acceleration is attributed to a true micellar catalysis, the remainder being ascribed to an increase in local reactant concentrations in the micelle.
- Wong,Connors
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p. 146 - 150
(2007/10/02)
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