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During the past decade a new concept has appeared in asymmetric catalysis involving the combination of a biocatalyst and a chemocatalyst in one 'pot' leading to efficient deracemization via dynamic kinetic resolution (DKR). Here, we outline the different strategies that have been developed for efficient chemoenzymatic DKR, in particular the powerful combination of an enzyme and a metal catalyst. 相似文献
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Antonio Caligiuri Paola D'Arrigo Thierry Gefflaut Gianluca Molla Loredano Pollegioni Elena Rosini 《Biocatalysis and Biotransformation》2013,31(6):409-413
Kinetic parameters of d-amino acid oxidase from R. gracilis (DAAO) towards d-2-naphthyl alanine (d-2-NAla) and of l-aspartate amino transferase (l-AAT) from Escherichia coli towards 2-naphthyl pyruvate (2-NPA) were measured. The two enzymes were then combined in a one-pot reaction in which DAAO was used to generate 2-NPA which was the substrate of l-AAT in the presence of cysteine sulphinic acid (CSA) as an amino donor. The combined reactions afforded enantiomerically pure l-2-NAla in almost quantitative yield. The extremely low water solubility of 2-NAla can be partially overcome by running the biotransformation in suspension with higher formal concentration. In these conditions multiple enzyme additions are required. 相似文献
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Prashant U. Naik Susheel J. Nara Jitendra R. Harjani Manikrao M. Salunkhe 《Journal of Molecular Catalysis .B, Enzymatic》2007,44(3-4):93-98
A hydroxyl group appended task specific ionic liquid was designed and synthesised. The ionic liquid was used as a vehicle for the substrate of our interest for lipase catalysed kinetic resolution. The ionic liquid anchored ibuprofen underwent Candida antarctica lipase catalysed hydrolysis yielding the S-enantiomer. The strategy facilitated easy post-resolution isolation of the enantiomers and also carries the prospect of recyclability. 相似文献
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Enzyme-catalysed transformations carried out in two-phase systems consisting of water and a water-immiscible organic solvent are discussed. The systems appear advantageous when substrates poorly soluble in water, such as steroids, are used. The methodology also makes possible the use of hydrolytic enzymes for the synthesis of ester bonds. Several applications of such two-phase systems are illustrated. The criteria that must be taken into consideration for selecting the most suitable organic solvents and the operational conditions are discussed. 相似文献
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Synapsis and strand exchange in the resolution and DNA inversion reactions catalysed by the beta recombinase
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In the presence of a sequence-independent chromatin-associated protein, such as Hbsu or HMGB, the β recombinase catalyses resolution between two directly oriented recombination sites (six sites) and both resolution and DNA inversion between two inversely oriented six sites. Assembly of the synaptic complex requires binding of the β recombinase to the six sites and the presence of Hbsu. Whether resolution or inversion will take place depends on the relative orientation of the two six sites, the level of DNA supercoiling and the amounts of Hbsu. In this work, the topologies of the products of the resolution and inversion reactions were analysed. The resolution reaction generated mainly singly catenated DNA circles, while DNA inversion gave rise to unknotted circles and small amounts of DNA molecules containing 3- or 5-noded knots. In spite of the distinctive features of the β system, the topology of synapsis and strand exchange during the resolution reaction is similar to that of Tn3 and γδ resolvases. The ability of the β recombinase to catalyse both inversion and resolution reactions probably reflects different possible architectures of the synaptic complex, which to a large extent depends on Hbsu. 相似文献
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M. A. P. J. Hacking F. van Rantwijk R. A. Sheldon 《Journal of Molecular Catalysis .B, Enzymatic》2000,9(4-6):183-191
The acylation of hydrazine, to afford the N,N′-diacyl derivatives, was catalysed by a number of lipases. The rates of the first and second steps depended on the lipase and the type of solvent used. Water, up to 0.4 M, had no detrimental effect on the yield and complete conversion to the N,N′-diacyl derivative was accomplished with some lipases. The hydrazide of 2-(4-isobutylphenyl)propanoic acid (ibuprofen), prepared by non-enzymatic reaction of ibuprofen methyl ester with hydrazine, acted as a nucleophile towards several lipases that do not accept ibuprofen derivatives as the acyl donor, but the enantiomer differentiation was inefficient in most cases. The best result was obtained with Pseudomonas lipoprotein lipase on EP 100 which formed the (R) enantiomer of the product (N-octanoyl-N′-2-(4-isobutylphenyl)propanoylhydrazine) with an enantiomeric ratio E of 26. 相似文献
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Golinelli-Pimpaneau B 《Current opinion in structural biology》2000,10(6):697-708
New structural data on nonhydrolytic antibody catalysts gained over the past two years confirm that antibodies elicited against transition-state analogues function by differential stabilisation of the transition-state over the ground state through electrostatic, van der Waals, cation-pi and hydrogen-bonding interactions. The lack of chemical catalysis correlates with the low catalytic efficiency. Novel strategies that precisely position a key functional residue in the antibody catalyst combining site have therefore emerged, as demonstrated by crystallographic studies. Whereas antibodies with a bulky residue at position H100c of hypervariable loop H3 adopt different cavity shapes, other antibodies share a common deep combining site. This structural restriction might reflect the use of similar hydrophobic haptens to generate the antibody; novel hapten design or new immunisation strategies may, in the future, lead to more structurally diversified active sites. 相似文献
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Dynamic kinetic resolution 总被引:2,自引:0,他引:2
The use of transition-metal-enzyme combinations to effect tandem in situ racemisation and resolutions has extended the scope of dynamic kinetic resolutions. This methodology has signalled a more proactive stance to the racemisation process, which has traditionally relied on more fortuitous approaches, namely the exploitation of labile substrates. The development and application of specific racemising enzymes such as mandelate racemase offers potential for future multienzyme dynamic kinetic resolutions. 相似文献
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Musa M. Musa 《Chirality》2020,32(2):147-157
Racemization is the key step to turn a kinetic resolution (KR), which suffers from the well-known drawback of being limited to a maximum yield of 50% with high enantiopurity, into a dynamic kinetic resolution (DKR) process. Enzyme-based racemization of enantiopure alcohols and amines has gained significant interest in recent years. This review covers recent advances in enzyme-based racemization approaches and their potential applications in bi-enzymatic DKR. 相似文献
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By using [3H]mannobiose as a labelled acceptor, it was possible to demonstrate transfer reactions catalysed by two beta-mannanases, with mannotetraose and mannopentaose as substrates. The enzyme from Streptomyces transfers one mannose unit from the oligosaccharides, whereas the enzyme from fenugreek (Trigonella foenum-graecum) seeds is able to transfer oligomannose residues. 相似文献
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M Kelly 《The Biochemical journal》1968,109(2):322-324
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The immobilisation of lipase from Pseudomonas stutzeri (Lipase TL®) by different entrapment protocols (sol–gel, static emulsion-silicone and direct entrapment in silicone spheres) is described for the first time. As this not very common commercial lipase has been recently reported as able to catalyse the dynamic kinetic resolution of benzoins (1,2-diaryl-2-hydroxyethanone structures) combined with a transition metal catalyst, although suffering a deactivation at high temperatures, the different immobilisation methodologies were tested with the aim of enhance lipase activity and stability in the above mentioned process. The enzyme immobilisation by silicone spheres entrapment was the most appropriate method, resulting in a considerable activation of this lipase. Furthermore, the high stability of this immobilised lipase at 60 °C, allowed the development of a “one pot” benzoin DKR process, reaching high conversions in short time, with a 30-fold increase of the productivity of the process due to the possibility of recycling and reuse of the catalyst. 相似文献
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Olga Klezovitch Yves Brandenburger Michle Geindre Jacques Deshusses 《FEBS letters》1993,320(3):256-260
The nature of reactions catalysed by yeast phosphatidylinositol synthase expressed in E. coli has been investigated. The single enzyme is shown to carry both CDP-diacylglycerol-dependent incorporation of inositol into phosphatidylinositol (Km for inositol of 0.090 mM) and a CDP-diacylglycerol-independent exchange reaction between phosphatidylinositol and inositol (Km for inositol of 0.066 mM). The exchange reaction and reversal of phosphatidylinositol synthase were both stimulated by CMP, but had different optimum pH and requirements for substrates. These results suggest that CMP-stimulated exchange and CMP-dependent reverse reactions are distinct processes catalysed by the same enzyme. phosphatidylinositol synthase. 相似文献
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Marie Zarevúcka Martin Rejzek Milan Pavlík Zdeněk Wimmer Jan Zima Marie-Dominique Legoy 《Biotechnology letters》1994,16(8):807-812
Summary The racemic cis and trans isomers 1a and 1b of 2-(4-methoxybenzyl)-1-cyclohexanol were subjects of an enzyme mediated resolution via esterification in organic solvents, in which the chiral esters 2a and 2b of the corresponding alcohols 4a and 4b, and the chiral alcohols 3a and 3b were obtained. The chemical yield and enantioselectivity of this enzymatic reaction have been found to depend mainly on (a) the structure of the substrate (cis or trans), (b) temperature, (c) the nature of the enzyme selected, and (d) the nature of the solvent. 相似文献
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F X Malcata H R Reyes H S Garcia C G Hill C H Amundson 《Enzyme and microbial technology》1992,14(6):426-446
This review focuses on the kinetics and mechanisms of reactions catalysed by immobilized lipases. The effects of pH, temperature, and various substances on the catalytic properties of immobilized lipases and on the processes by which they are deactivated are reviewed and discussed. 相似文献