FRET-based fluorescence probes for hydrolysis study and pig liver esterase activity

New fluorescent probes based on simple organic synthesis were designed and synthesized, and their hydrolysis catalyzed via base and pig liver esterase (PLE) was studied using FRET (fluorescence resonant energy transfer), with 1-naphthylacetic group as a donor and dansyl group as an acceptor. By simultaneous recording of changes of the donor fluorescence intensities, kinetic parameters for base-catalyzed and PLE-catalyzed hydrolysis can be determined. The presented FRET assay is a convenient and simple method and both fluorescent probes are good real-time indicators for the analysis of ester hydrolysis such as PLE activities.     

Enantioselective hydrolysis of dialkyl 3-monosubstituted glutarates with pig liver esterase: Structure-optical purity relationships

Dialkyl 3-monosubstituted glutarates are subjected to hydrolysis with pig liver esterase to afford the corresponding chiral half-esters. Synthetically useful half-esters of higher optical purity are obtained from the prochiral substrates of more hydrophobic nature.     

Chemoenzymatic synthesis of an α-substituted serine derivative

An asymmetric synthesis of an α-substituted serine derivative was achieved by employing PLE-catalyzed hydrolysis of a prochiral malonate derivative, and the absolute configuration of the hydrolyzed product was unambiguously determined by the X-ray analysis of a camphorsulfonic acid derivative.     

Activation of pig liver esterase in organic media with organic polymers: application to the enantioselective acylation of racemic functionalized secondary alcohols

Pig liver esterase (PLE) shows practically no activity in acylation of alcohols with vinylic esters in organic solvents. However, addition of methoxypoly(ethylene glycol) (MPEG), bovine serum albumin (BSA), TentaGelAmino resin (TGA), or aminomethyl polystyrene (AMPS) confers activity to PLE in acylation of alcohols with vinyl propionate in organic solvents of low water content. Polymer-activated PLE showed high enantioselectivities (E > 100) in the acylation of racemic 1-alkoxy-, 1-ethylsulfanyl-, and 1-fluoro-3-aryl-2-propanols as well as racemic 1-phenoxy-2-propanol and racemic 1-methoxy-2-phenoxy-2-propanol. The synthetic utility of polymer-activated PLE has been demonstrated by the gram-scale resolution of 1-methoxy-3-phenyl-2-propanol, 1-ethylsulfanyl-3-phenyl-2-propanol, 1-methoxy-3-p-methoxyphenyl-2-propanol, 1-fluoro-3-phenyl-2-propanol, and 1-methoxy-3-phenoxy-2-propanol. In PLE-catalyzed acylation of alcohols with vinyl propionate, acetaldehyde and propionic acids, both being detrimental to the enzyme, are formed as byproducts. In addition, the water content of the system, which is critical for the activity of pig liver esterase, is lowered because of a competing enzymatic hydrolysis of the acyl donor. The polymers TGA, BSA, and AMPS not only scavenge the aldehyde and the acid through imine formation and neutralization, respectively, but replenish at least in part also the water consumed in the competing hydrolysis of the acyl donor. A recovery of PLE together with the polymer was achieved without major loss of activity through their immobilization on a water-saturated polyaramide membrane, which occurs spontaneously in organic solvents.     

Development of a practical mass spectrometry based assay for determining enantiomeric excess. A fast and convenient method for the optimization of PLE-catalyzed hydrolysis of prochiral disubstituted malonates

A practical mass spectrometry-based enantioselectivity assay is presented which makes use of enantiomerically enriched, but not enantiomerically pure, probe molecules readily obtained from esterase hydrolysis of prochiral malonates. The technique presented here allows us to recycle materials obtained from esterase hydrolysis which give substantial, but synthetically insufficient, enantiomeric excess as probe molecules in an enantioselectivity assay. The enantiomerically enriched products are esterified using deuterium-labelled alcohol. The enantiomeric excess is measured using mass spectrometry (LC–MS and LDI) by measuring the D₅/H₅ ratio in the resulting products obtained from an enzymatic hydrolysis. The D₅/H₅ ratio is corrected to account for the enantiomeric purity of the probe. Herein we report the results obtained from Pig Liver Esterase hydrolyses of prochiral malonate esters and outline the strengths and limitations of this approach to enantioselectivity determinations. This assay strategy was able to identify reaction conditions that led to an improvement in ee from 70% ee to >97% ee in the PLE-catalyzed hydrolysis of a prochiral malonate used to prepare unnatural serine analogues.     

On the applicability of the Jones active site model of pig liver esterase to S-chiral and prochiral sulfinyl substrates

A series of racemic methyl sulfinylacetates was hydrolyzed in the presence of pig liver esterase (PLE) under kinetic resolution conditions to give the corresponding S-chiral sulfinylacetic acids and recovered esters in moderate enantiomeric purity. The Jones active site model was found to be suitable for explaining the enantioselectivity of the above reaction and for the PLE-mediated desymmetrization of prochiral sulfinyldicarboxylates.     

猪肝酯酶在不对称合成中的应用

猪肝酯酸PLE(Pig Liver Esterase)对双酯具有特殊的不对称水解性,而且可获得高产率和高光学纯的不对称水解产物。本文简要介绍PLE作为一种有效的酶催化剂,在温和的条件下,对双酯的不对称水解反应和在不对称合成中应用的近况。     

Introduction of a quaternary stereogenic center to oxindole using cholinesterase-catalyzed asymmetric hydrolysis

Prochiral diesters bearing an oxindole skeleton were efficiently prepared from oxindole. Cholinesterase-catalyzed hydrolysis of prochiral dipropionate afforded an optically active monoalcohol of 95% e.e. The obtained monoalcohol might find use as a versatile intermediate in the enantioselective synthesis of indole alkaloids.     

Enzymatic hydrolysis of prochiral cis-1,4-diacyl-2-cyc-lopentenediols: preparation of (1S,4R)-and (1R,4S)-4-hydroxy-2-cyclopentenylderivatives,versatile building blocks for cyclopentanoid natural products.

The enzymatic hydrolysis of prochiral diesters 1 was studied in presence of seven enzymatic systems, resulting in the enantioselective preparation of both enantiomeric series of chiral building blocks 2 - 4 and $\text{ent}$- 2 - 4 on a preparative scale.     

Pig Liver Esterase-catalyzed Hydrolysis of Three Diesters of meso-Bicyclic Dicarboxylic Acid and Three Tetraesters of Tetrahydrofuran-2, 3,4,5-tetracarboxylic Acid

IntroductionPig liver esterase(PLE) is one of the most useful enzymes for the enantioselective hydrolysis of ester groups, which has been demonstrated by numerous examples. The enantioselectivity of PLE towards the hydrolysis of one of the diesters with prochiral centers or meso-diesters has been the subject of extensive investigations['--']. The hydrolysis of the dimethyl esters of some symmetrical dicarboxylic acids in the presence of PLE gave encouraging results[5-7].In order to prepare…     

Enantioselective hydrolysis of cis -1,2-diacetoxycycloalkanedimethanols:enzymatic preparation of chiral building blocks from prochiral meso -substrates.

The enzymatic hydrolysis of the prochiral title compounds (=1a) - (=f) in presence of porcine liver esterase (PLE) and lipase from porcine pancreas (PPL) was studied, resulting in the preparation of the chiral monoacetates (=2b) - (=f) with high (72–99%e.e.) enantiomeric purities.     

Practical selective monohydrolysis of bulky symmetric diesters

The highly efficient selective monohydrolysis reaction we previously reported has been applied to monohydrolysis of several bulkyl symmetric diesters, including diethyl esters, dipropyl esters, and dibutyl esters. A greater proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH appear to help improve the reactivity of bulky diesters compared to the corresponding dimethyl esters. The procedure is mild and practical, yielding the corresponding half-esters in high yields under simple conditions.     

Practical selective monohydrolysis of bulky symmetric diesters: Comparing with sonochemistry

The conditions of the practical selective monohydrolysis of symmetric diesters we previously reported have been modified and applied to selective monohydrolysis of bulky symmetric diesters. While ultrasound is generally considered effective for two-phase reactions, its effect actually turned out to be rather marginal. Instead, use of a larger proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH helped enhance the reaction rates and improve the yields of the half-esters. The reactions are simple, mild and practical without special devices.     

Bifunctional chiral synthons via biochemical methods. : VI. C5 isoprenoid units.

Two methods for the preparation of the isoprenoid chiron $\text{4}$ have been developed using a microbial kinetic resolution of $\text{5}$ and an enantiotopically selective hydrolysis of $\text{7}$ catalyzed by PLE.     

Asymmetric synthesis of organometallic reagents using enzymatic methods

The use of enzymatic catalysis in the synthesis and resolution of organometallic complexes is reviewed and discussed. Examples show the potential of biological catalysts for oxidation, reduction, hydrolysis, and esterification of both transition metal and main group organometallic substrates. Chirality in organometallic complexes caused by the presence of chiral carbon centers in substituent groups, tetrahedral or pseudotetrahedral metal centers, and planes of asymmetry can all be recognized by whole cell or isolated enzyme catalysts. Biocatalysts that achieve high levels of kinetic resolution are described. Other catalysts that produce high levels of asymmetric induction in reactions of a prochiral substrate are also described.     

A Study of Stereoselective Hydrolysis of Symmetrical Diesters with Pig Liver Esterase

Pig liver esterase-(PLE) catalyzed hydrolysis of dimethyl esters of symmetrical dicarboxylic acids, including meso-diacids, cis-1,2-cycloalkanedicarboxylic acids, and diacids with a prochiral center, was studied with 14 substrates. The products of these stereoselective hydrolyses are chiral monoesters of dicarboxylic acids, with an enantiomeric excess (e.e.) from 10% to 100%. Some of these optically active monoesters are valuable synthons in natural products synthesis. An additivity pattern of α- and β-substituents with the glutaric esters on the stereoselectivity of enzymatic hydrolysis was observed. Analysis of the experimental results leads to a model of enzyme stereoselectivity of diester hydrolysis in which the substitution pattern at α- and β-C-atoms is found to determine the absolute configuration of the resulting monoester.     

Highly efficient selective monohydrolysis of dialkyl malonates and their derivatives

The highly efficient selective monohydrolysis of symmetric diesters has been applied to monohydrolysis of several dialkyl malonates and their derivatives. The best conditions apply 0.8-1.2 equiv of aqueous KOH with a co-solvent, THF or acetonitrile, at 0 °C. The procedure is highly practical, yielding the corresponding half-esters in high yields in a straightforward manner, without inducing decarboxylation. It was found that the selectivity tends to become higher with increased hydrophobicity.     

Lipase mediated sequential resolution of aromatic β-hydroxy esters using fatty acid derivatives

The lipase-catalyzed kinetic resolution of a series of aromatic β-hydroxy esters in organic media has been investigated. Decanoic acid and its esters were successfully used as acyl donors for selective O-acylation. The regio- and enantioselective enzymatic hydrolysis of the decanoate moiety of the diesters was also investigated. The effects of water, reaction temperature, and solvent type, and also the influence of substrates structure on the catalytic behavior of potential commercially available lipases were studied. A novel procedure was developed for the efficient and highly stereoselective synthesis of both enantiomers of both novel and known target compounds.     

Enantioselective preparation of N-chirogenic tertiary amine oxides

We found that PLE can be used as an efficient catalyst for desymmetrization of prochiral tertiary amine N-oxides and demonstrated that they were hydrolyzed by PLE efficiently to afford N-chirogenic tertiary amine oxides up to 99% ee in moderate to good yields.     

Complementary lipase-mediated desymmetrization processes of 3-aryl-1,5-disubstituted fragments. Enantiopure synthetic valuable carboxylic acid derivatives

Desymmetrizaton enzymatic processes have been extensively studied searching for optimal methods of producing enantioenriched monoacetates from prochiral diols and diesters. AK lipase has been found as an excellent biocatalyst for the desymmetriaztion of a series of previously synthesized 3-arylpentane-1,5-diols derivatives. The access to (S)- or (R)-monoacetates in high optical purity (86-99% ee) has been possible by using acetylation or hydrolysis reactions, respectively, where the reaction parameters have been optimized in terms of source and amount of biocatalyst, temperature, solvent, and reaction time. The synthetic potential of enantiopure monoesters has been demonstrated by using these interesting chiral building blocks for the preparation of novel enantiopure carboxylic acid derivatives.