A

Figure 6 Enantioselective oxidation of secondary alcohols with secondary alcohol dehydrogenase (SADH), from a thermophilic bacterium (log E is used in Figure 6 Enantioselective oxidation of secondary alcohols with secondary alcohol dehydrogenase (SADH), from a thermophilic bacterium (log E is used in a similar reaction with 2-pentanol raised the Tr to 70 C, and that with 2-hexanol further raised the Tr to 260 0C. These results suggest that the chain length changes the structure of the...

Enzymatic synthesis of functional phenolic polymers

Poly(2,6-dimethyl-1,4-oxyphenylene) (poly(phenylene oxide), PPO) is a material widely used as high-performance engineering plastics, thanks to its excellent chemical and physical properties, e.g., a high T (ca. 210 C) and mechanically tough property.151 PPO was first prepared from 2,6-dimethylphenol monomer using a copper amine catalyst system. 2,6-Dimethylphenol was also polymerized via HRP catalysis to give a polymer exclusively consisting of 1,4-oxyphenylene unit,177 while small amounts of...

Enzymatic oxidative polymerization of phenols

Peroxidase-catalyzed oxidative coupling of phenols proceeds fast in aqueous solutions, giving rise to the formation of oligomeric compounds. However, the resulting oligomers have not been well characterized, since most of them show low solubility towards common organic solvents and water. In 1987, enzymatic synthesis of a new class of phenolic polymers was first reported.150 An oxidative polymerization of p-phenylphenol using HRP as catalyst was carried out in a mixture of water and...

Reaction of allyl tetraacetyl fDglucopyranoside and phenyl boronic acid2425

Golden root (Roseroot, Rhodiola rosea L., Crassulaceae) has been used for a long time as a resource in Chinese traditional medicine. Phenylpropenoid glu-coside, such as Rosin (cinnamyl O-P-D-glucopyranoside 118a), was isolated from R. rosea as one of the major active ingredients and reported to be pharmacologically active as antioxidants and neurostimulants. Moreover, some other phenylpropenoid glucoside analogs have been isolated as bioactive substances. For instance, Sachaliside 1 (Triandrin...

References

Kielbasinski, P. Chiral Sulfur Reagents Applications in Asymmetric and Stereoselective Synthesis CRC Press Boca Raton, 1997. (b) Pietrusiewicz, K. M. Zablocka, M. Chem. Rev. 1994, 94, 1375-1411. (c) Kafarski, P. Lejczak, B. Phosphorus Sulfur Silicon 1991, 63, 193-215. (d) Palacios, F. Alonso, C. de los Santos, J. M. Chem. Rev. 2005, 105, 899-931. 2. Kielbasinski, P. Mikolajczyk, M. In Hydrolytic Enzymes in the Synthesis of Non-racemic Heteroorganic Compounds...

Cchiral amino phosphorus compounds

C-Chiral amino phosphorus compounds, particularly 1-amino- and 2-aminoalkanephosphonic acids, have been a subject of interest for organic chemists due to their interesting biological activity.1cd Among many methods of their stereoselective synthesis, some enzymatic approaches have been reported, which constitute a nice alternative to chemical procedures. Stereoselective hydrolysis of racemic 1-(N-phenylacetylamino) alkanephos-phonic acids performed in the presence of penicillin acylase under...

Polycondensation of dicarboxylic acid derivatives and glycols to polyesters

So far, various dicarboxylic acid derivatives, dicarboxylic acids, their activated and non-activated esters, cyclic acid anhydrides, and polyanhydrides have been polymerized with glycols through lipase catalysis to give polyesters. Many diacids are commercially available however, their enzymatic reactivity is relatively low. Therefore, the enzymatic polymerization of dicarboxylic acids and glycols was often carried out under vacuum for production of high molecular weight polyesters.56 57 In the...

Isolation of microorganisms having aldoxime dehydratase activity12

By using acclimation for 3-4 months of soil microorganisms to a medium containing Z-phenylacetaldoxime (PAOx), a degrader Bacillus sp. OxB-1 was isolated, which has an activity of converting PAOx to phenylacetonitrile (PAN) and a strong nitrilase activity. Partial purification of the enzyme activity revealed that the enzyme catalyzed the stoichiometric conversion of PAOx to PAN. On the other hand, we isolated a degrader of E-pyridine-3-aldoxime (PyOx), Rhodococcus sp. YH3-3 from soil after 6...

Enzymatic synthesis and biological properties of flavonoid polymers

Bioactive polyphenols are present in a variety of plants and used as important components of human and animal diets.215 Flavonoids are a broad class of low molecular weight secondary plant polyphenolics, which are benzo-7-pyrone derivatives consisting of phenolic and pyrane rings. Their biological and pharmacological effects including antioxidant, antimutagenic, anticarcinogenic, antiviral, and anti-inflammatory properties have been demonstrated in numerous human, animal, and in vitro studies....

Ringopening polymerization to polyesters

Various cyclic esters have been subjected to lipase-catalyzed ring-opening polymerization. Lipase catalyzed the ring-opening polymerization of 4- to 17-membered non-substituted lactones.16-18 In 1993, it was first demonstrated that medium-size lactones, 8-valerolactone 8-VL, six-membered and e-caprolactone e-CL, seven-membered , were polymerized by lipases derived from Candida cylindracea, Burkholderia cepacia lipase BC , Pseudomonas fluorescens lipase PF , and porcine pancreas PPL .1920...

Enzymatic synthesis of functional polyesters

Lipase catalysis is often used for enantioselective production of chiral compounds. Lipase induced the enantioselective ring-opening polymerization of racemic lactones. In the lipase-catalyzed polymerization of racemic P-BL, the enantioselec-tivity was low an enantioselective polymerization of P-BL occurred by using thermophilic lipase to give R -enriched PHB with 20-37 enantiomeric excess The enantioselectivity was greatly improved by the copolymerization with 7- or 13-membered non-substituted...

Possible use of enzymes for the direct carboxylation of organic substrates

Department of Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu, Japan The occurrence of the enzymes catalyzing the Kolbe-Schmitt carboxylation has been shown, and the characterization of these enzymes has been reviewed. Among them, 2,6-dihydroxybenzoate decarboxylase and pyrrole-2-carboxylate decarboxylase efficiently catalyze the reverse carboxylation reaction and accumulate high concentration of 2,6-dihydroxybenzoate from 1,3-dihydroxybenzene and...

Oxidative decarboxylation of hydroxycarboxylic acids

As mentioned in the introductory part, stereochemical course of the conversion of isocitric acid to a-ketoglutaric acid in TCA cycle is completely enantiose-lective although the reaction does not form an asymmetric carbon in the usual metabolic path. If such type of oxidative decarboxylation can be applied to synthetic compounds, it is expected that an entirely new type of asymmetric biotransformation will be developed. Aiming at the feasibility study of such type of asymmetric decarboxylation,...

Tertiary structure and mutagenesis studies

TKase is a homodimeric protein with a subunit of about 70 kDa. The X-ray structures of TKase of E. coli,62 S. cerevisiae,61-63 67 Leishmania mexicana6 amp and mize69 have been solved. In addition, the crystal structures of a number of site-directed mutants have been determined.70-73 Schneider and co-workers have reported a series of studies in which they have mutated important residues of active site of TKase to elucidate the reaction mechanism and explain the origin of the stere-ospecificity...

Biocatalytic Properties Of Recombinant Available Bvmos

The list of heterologously expressed type I BVMOs has grown significantly in recent years Table 1 . Except for BVMOs primarily acting on small cyclic ketones cyclopentanone and cyclohexanone 1920, variants specific for larger cyclic ketones cyclododecanone and cyclopentadecanone have also been discovered.2122 Additionally, BVMOs that readily accept aromatic ketones 4-hydroxyacetophenone and phenylacetone derivatives have been described.1723 Also, a BVMO acting on steroids has been reported.24...

Conclusions Future Directions

As each BVMO is limited in substrate specificity, it is crucial to have a large collection of these oxidative biocatalysts available. Except for expanding the scope of possible reactions, a large toolbox of BVMOs would also increase the chance of being able to perform any wanted specific chemo-, regio- and or enantioselective reaction. This contrasts with the present situation as only a relatively small number of BVMOs can be exploited for biocatalytic purposes. Therefore, it is still crucial...

Introduction

The Baeyer-Villiger oxidation reaction was discovered more than 100 years ago by Adolf von Baeyer and Victor Villiger.1 By this reaction, ketones are converted into the corresponding esters. In organic chemistry, peracids are commonly used as catalyst to perform this atypical oxidation reaction that results in oxygen insertion into a carbon carbon bond Fig. 1 . Already in 1948 it was recognized that enzymes that catalyze Baeyer-Villiger reactions exist.2 This was concluded from the observation...

Future Directions in Biocatalysis

Tokyo Institute of Technology, Yokohama, Japan Amsterdam Boston Heidelberg London New York Oxford Paris San Diego San Francisco Singapore Sydney Tokyo Radarweg 29, PO Box 211, 1000 AE Amsterdam, The Netherlands Linacre House, Jordan Hill, Oxford OX2 8DP, UK Copyright 2007 Elsevier B.V. All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the...

Hydroxybenzoate decarboxylase EC 41161

4-Hydroxybenzoate decarboxylase EC 4.1.1.61 of anaerobe C. hydroxyben-zoicum was purified and characterized for the first time.20 It has an apparent molecular mass of 350 kDa and consists of six identical subunits of 57 kDa. The temperature optimum for the decarboxylation is approximately 50 C, the optimum pH being 5.6-6.2. The activation energy for decarboxylation of 4-hydroxybenzoate is 65kJmol-1 20-37 C . The enzyme also catalyzes the decarboxylation of 3,4-dihydroxybenzoate. The apparent Km...

Dihydroxybenzoate decarboxylase

A novel decarboxylase, 2,6-dihydroxybenzoate decarboxylase, was found in Agrobacterium tumefaciens IAM 12048 at first.36 Thereafter, the same activity was found in Rhizobium species by two groups independently.37 38 Furthermore, Pandoraea sp. 12B-2, the most powerful producer of 2,6-dihydroxybenzoate decarboxylase, was isolated.39 These enzymes have been purified and characterized. 2,6-Dihydroxybenzoate decarboxylase activity of these bacteria was induced specifically by 2,6-dihydroxybenzoate....

Redesign of BVMOs

For enzyme redesign studies, structural information of a targeted biocatalyst is very valuable. However, at present, no structure of the well-studied BVMO, CHMO, is available. In order to obtain a predictive structural model of the active site of CHMO, a cubic space model has been built based on the substrate acceptance of this biocatalyst.53 While this model can predict to some extent the specificity and selectivity of CHMO, it is of little use for enzyme redesign studies. However, even if no...

Discovery of novel BVMOs

While the number of available recombinant BVMOs has grown significantly over the last few years, there is still a demand for other BVMOs to expand the biocat-alytic diversity. Most BVMOs that have been described are dedicated to efficiently Figure 3 Illustration of overlapping substrate specificities of four BVMOs. Cyclohexanone monooxygenase CHMO , cyclopentanone monooxygenase CPMO , 4-hydroxyacetophenone monooxygenase HAPMO and phenylacetone monooxygenase PAMO . For each enzyme, several...

Crystal Structures Of Hydroxynitrile Lyases And Mechanism Of Cyanogenesis

The properties and characteristics of the five HNLs used as catalysts in stereoselective syntheses are listed in Table 2. The crystal structures of these HNLs have been determined during the last decade. From the crystal structures and kinetic measurements, the mechanistic pathways of cyanogenesis could be established. HNL-catalyzed addition of HCN to 4-substituted cyclohexanones R CN S -MeHNL R U M R -PaHNL R OH Scheme 9 Stereoselective synthesis of cis-p-menthane-1,7,8-triol A and...

Exploring sequenced metagenomes for novel BVMOs

Nowadays, the genomes of a wide variety of organisms have been sequenced and are publicly available, offering a new and efficient way of retrieving BVMO genes. Currently, as genome sequences of over 600 microbes are available see it is attractive to look directly into this pool of genes in silico without growing and isolating any microorganism. In addition to the database of partially and fully sequenced genomes, it is also informative to survey the database of sequenced environmental genomes....

Screening For New Microbial Enzymes By Enrichment And Acclimation Culture Techniques

Little is known about the substrate specificities of most of the enzymes as compared with common reagents used in organic synthesis. The velocity of the enzymatic reactions is much affected by the neighboring substituents it cannot be predicted whether an unnatural chemical can be a substrate or not with most of the enzymes. Therefore, we screen microorganisms for an enzyme when i no information is available for the desirable reaction, ii nothing is known about the specific reaction but a...

Screening the metagenome for novel BVMOs

Except for exploring sequenced genomes, yet other interesting approaches for discovering novel BVMOs exist. A recent development in the area of biocatalyst discovery is the exploitation of metagenomic DNA libraries. By this methodology, DNA is directly isolated from a certain sample that is expected to contain a variety of microbes e.g., soil . Subsequently, the obtained DNA is randomly fragmented and cloned into a suitable vector and expression host. The resulting gene library, containing a...

Stereoselective synthesis of substituted cyclohexanone cyanohydrins

Substituted 1-hydroxy cyclohexane-1-carboxylic acids, which could be prepared from the corresponding cyanohydrins by acid hydrolysis as described above, are important as pharmaceuticals and plant-protective agents.33 Although the compounds derived from 2- and 3-cyclohexanones have two stereogenic centers, stereoselective syntheses of these interesting products have been published only very recently.34 Completely unexpected are the results of HNL-catalyzed additions to 4-substituted...

Removal Of Organic And Inorganic Substances In Wastewater

The prudent disposal of large quantities of agricultural and domestic wastewaters is a major concern in our modern society. Raw wastewaters most often contain significant amounts of bioavailable organic substances such as phenols, endocrine disrupters, and inorganic substances such as ammoniate, nitrate, and phosphate. To remove these substances, algae and microalgae were used.18 For example, inorganic substances such as ammonium,19 phosphorous,18 and arsenate20 compounds and organic substances...

Biotransformation in ionic liquid

Department of Materials Science, Faculty of Engineering, Tottori University, Tottori, Japan The use of ionic liquids ILs to replace organic or aqueous solvents in biocatalysis processes has recently gained much attention and great progress has been accomplished in this area lipase-catalyzed reactions in an IL solvent system have now been established and several examples of biotransformation in this novel reaction medium have also been reported. Recent developments in the application of ILs as...

Phenolphosphate carboxylase EC 411 in Thauera aromatica

Hydroxybenzoate Decarboxylase

The anaerobic metabolism of phenol in T. aromatica is initiated by the ATP-dependent conversion of phenol to phenylphosphate catalyzed by phenylphosphate synthase EC 2.7.9.- . The subsequent para carboxylation of phenylphosphate to 4-hydroxybenzoate is catalyzed by phenolphosphate carboxylase EC 4.1.1.- .8'29'30 Both enzyme activities are induced in cells grown anoxially on phenol and nitrate and not in cells grown on 4-hydroxybenzoate, the product of this process. Further metabolism of...