共查询到20条相似文献,搜索用时 15 毫秒
1.
Patel RN 《Current opinion in biotechnology》2001,12(6):587-604
There has been an increasing awareness of the enormous potential of microorganisms and enzymes for the transformation of synthetic chemicals with high chemo-, regio- and enantioselectivity. Chiral intermediates and fine chemicals are in high demand, both from the pharmaceutical and agrochemical industries, for the preparation of bulk drug substances and agricultural products. Biocatalytic processes have been described for the synthesis of chiral intermediates for beta3- and beta2-receptor agonists, antihypertensive drugs, antiviral agents, melatonin receptor agonists, anticholesterol and anticancer drugs, and drugs to treat Alzheimer's disease. 相似文献
2.
Biocatalytic combinatorial synthesis 总被引:2,自引:0,他引:2
Combinatorial biocatalysis, based on a principle of the combinatorial use of biosynthetic steps rather than the combinatorial use of reagents, offers a complementary approach to combinatorial chemistry, which, used individually or in connection with synthetic organic transformations, provides access to analogues not readily accessible by chemical synthetic means alone. The issues and strategies particular to this approach are discussed. Examples are given demonstrating these principles as well as the unique advantages of achieving chemo-, regio- and stereoselectivity under mild reaction conditions that biocatalytic methods offer. 相似文献
3.
Biocatalytic synthesis of vanillin 总被引:6,自引:0,他引:6
The conversions of vanillic acid and O-benzylvanillic acid to vanillin were examined by using whole cells and enzyme preparations of Nocardia sp. strain NRRL 5646. With growing cultures, vanillic acid was decarboxylated (69% yield) to guaiacol and reduced (11% yield) to vanillyl alcohol. In resting Nocardia cells in buffer, 4-O-benzylvanillic acid was converted to the corresponding alcohol product without decarboxylation. Purified Nocardia carboxylic acid reductase, an ATP and NADPH-dependent enzyme, quantitatively reduced vanillic acid to vanillin. Structures of metabolites were established by (1)H nuclear magnetic resonance and mass spectral analyses. 相似文献
4.
Palcic MM 《Current opinion in biotechnology》1999,10(6):616-624
Tremendous advances in biocatalytic approaches to oligosaccharide synthesis have taken place in the past two years. The use of isolated enzymes, both glycosyltransferases and glycosidases, or engineered whole cells allows the preparation of natural oligosaccharides and analogs required for glycobiology research. 相似文献
5.
The biocatalytic synthesis of fluorinated polyesters from activated diesters and fluorinated diols has been investigated. The effects of time, continuous enzyme addition, enzyme concentration, and diol chain length were studied to determine the factors that would limit chain extension, such as enzyme inactivation, enzyme specificity, the equilibrium position for the reaction, hydrolytic side reactions, and polymer precipitation. An enzyme screen demonstrated that only Novozym 435, an immobilized lipase from Candida antarctica, was effective in producing the fluorinated polyester. Molecular weight and polydispersity analyses were performed by means of gel permeation chromatography. End group analysis was accomplished through the use of matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. Polymer molecular weight steadily increased and then leveled off after approximately 30 h, with a weight average molecular weight of approximately 1773. The majority of the polymer chains were terminated with either hydroxyl or vinyl groups. Polymers that were synthesized from bulk monomers had higher molecular weights, but high enzyme concentrations were required. Enzyme specificity toward shorter chain fluorinated diols appeared to be the governing factor in limiting chain growth. However, polymer molecular weight increased further (M(w) = 8094) when a fluorinated diol that contained an additional methylene spacer between the fluorine atoms and hydroxyl groups was used. 相似文献
6.
The enzymatic preparation of optically pure tertiary alcohols under sustainable conditions has received much attention. The
conventional chemical synthesis of these valuable building blocks is still hampered by the use of harmful reagents such as
heavy metal catalysts. Successful examples in biocatalysis used esterases, lipases, epoxide hydrolases, halohydrin dehalogenases,
thiamine diphosphate-dependent enzymes, terpene cyclases, -acetylases, and -dehydratases. This mini-review provides an overview
on recent developments in the discovery of new enzymes, their functional improvement by protein engineering, the design of
chemoenzymatic routes leading to tertiary alcohols, and the discovery of entirely new biotransformations. 相似文献
7.
Sanjib Kumar Karmee 《Applied microbiology and biotechnology》2009,81(6):1013-1022
Ascorbyl fatty acid esters act both as antioxidants and surfactants. These esters are obtained by acylation of vitamin C using
different acyl donors in presence of chemical catalysts or lipases. Lipases have been used for this reaction as they show
high regioselectivity and can be used under mild reaction conditions. Insolubility of hydrophilic ascorbic acid in non-polar
solvents is the major obstacle during ascorbic acid esters synthesis. Different strategies have been invoked to address this
problem viz. use of polar organic solvents, ionic liquids, and solid-phase condensation. Furthermore, to improve the yield
of ascorbyl fatty acid esters, reactions were performed by (1) controlling water content in the reaction medium, (2) using
vacuum to remove formed volatile side product, and (3) employing activated acyl donors (methyl, ethyl or vinyl esters of fatty
acids). This mini-review offers a brief overview on lipase-catalyzed syntheses of vitamin C esters and their biotechnological
applications. Also, wherever possible, technical viability, scope, and limitations of different methods are discussed. 相似文献
8.
《Biocatalysis and Biotransformation》2013,31(2-3):87-95
AbstractThe preparation of a series of novel chiral N-(2-hydroxylalkyl)-acrylamides through a lipase-catalyzed resolution of racemic alkanolamines is described. The absolute stereochemistry and enantiomeric excess of the products were determined by a modified Mosher's method. The method was validated for this particular case by the synthesis of an enantiomerically pure product. Moreover, the stereoselective behavior of the lipase in this reaction is discussed. 相似文献
9.
G. V. Otrokhov O. V. Morozova I. S. Vasil’eva G. P. Shumakovich E. A. Zaitseva M. E. Khlupova A. I. Yaropolov 《Biochemistry. Biokhimii?a》2013,78(13):1539-1553
Enzymatic methods of synthesis of conducting polymers, physicochemical properties of the resulting products, and mechanisms of the reactions are considered. The enzymes involved in oxidative polymerization of monomers are briefly characterized. Examples of practical application of enzymatically synthesized conducting polymers are given. 相似文献
10.
11.
12.
Enzymatic synthesis of chiral intermediates for pharmaceuticals 总被引:1,自引:0,他引:1
Patel R Hanson R Goswami A Nanduri V Banerjee A Donovan MJ Goldberg S Johnston R Brzozowski D Tully T Howell J Cazzulino D Ko R 《Journal of industrial microbiology & biotechnology》2003,30(5):252-259
There has been an increasing awareness of the enormous potential of microorganisms and enzymes for the transformation of synthetic chemicals with high chemo-, regio- and enatioselective manner. Chiral intermediates are in high demand by pharmaceutical industries for the preparation bulk drug substances. In this review article, microbial/enzymatic processes for the synthesis of chiral intermediates for antihypertensive drugs, melatonin receptor agonists, and beta3-receptor receptor agonists are described. 相似文献
13.
Biocatalytic synthesis of enantiomerically pure compounds for pharmaceutical intermediates is gaining momentum. This is the result of advances in genomics, screening and evolution technologies leading to the increased availability of new and robust biocatalysts suited for industrial-scale application, and is stimulated by an increased demand for catalysts that are able to address the increased complexity of active pharmaceutical ingredients. The vast majority of biotransformation reactions for the manufacturing of optically active pharmaceutical intermediates are still based on enantioselective ketone reductions and enantiospecific hydrolyses. This review aims to point at alternative reaction types and integrated multi-enzymatic steps that are emerging in large-scale applications. 相似文献
14.
Nazari K Adhami F Najjar-Safari A Salmani S Mahmoudi A 《Biochemical and biophysical research communications》2011,(4):901-903
Micelle-templated polyguaiacol nanowires were successfully prepared via polymerization oxidation of guaiacol (o-methoxy phenol) by peroxidase enzyme in the presence of hydrogen peroxide at mild reaction conditions. The dimensions of the prepared nanowires were controlled by tuning the size and shape of the micelle structure via changing and controlling the type, chain length and molar concentrations of the ionic surfactant. The progress of the reaction and estimation of the size of soft micellar templates were followed by UV–Vis spectroscopy and dynamic light scattering (DLS). The resulting micelle encapsulated or purified polyguaiacol nanowires were characterized using transmission electron microscopy (TEM). 相似文献
15.
Hydrolase-catalysed synthesis of peroxycarboxylic acids: Biocatalytic promiscuity for practical applications 总被引:1,自引:0,他引:1
Carboni-Oerlemans C Domínguez de María P Tuin B Bargeman G van der Meer A van Gemert R 《Journal of biotechnology》2006,126(2):140-151
The enzymatic promiscuity concept involves the possibility that one active site of an enzyme can catalyse several different chemical transformations. A rational understanding of the mechanistic reasons for this catalytic performance could lead to new practical applications. The capability of certain hydrolases to perform the perhydrolysis was described more than a decade ago, and recently its molecular basis has been elucidated. Remarkably, a similarity between perhydrolases (cofactor-free haloperoxidases) and serine hydrolases was found, with both groups of enzymes sharing a common catalytic triad, which suggests an evolution from a common ancestor. On the other hand, several biotechnological applications derived from the capability of hydrolases to catalyse the synthesis of peracids have been reported: the use of hydrolases as bleaching agents via in situ generation of peracids; (self)-epoxidation of unsaturated fatty acids, olefins, or plant oils, via Prileshajev epoxidation; Baeyer-Villiger reactions. In the present review, the molecular basis for this promiscuous hydrolase capability, as well as identified applications are reviewed and described in detail. 相似文献
16.
17.
A second high-yielding bioorganic synthesis of the highintensity sweetener sucralose (4,1',6'-trichloro-4,1',6'-trideoxygalactosucrose) is described. This procedure involves the chemical chlorination of raffinose to form a novel tetrachloroaffinose intermediate (6,4',1',6'-tetrachloro-6,4',1',6'-tetradeoxygalactoraffinose; TCR) followed by the enzymic hydrolysis of the alpha-1-6 glycosidic bond of TCR to give sucralose and 6-chlorogalactose. Commercial enzyme preparations and microorganisms were screened to select alpha-galactosidases which have high catalytic activity on this compound. The most active enzyme was produced by a strain of Mortierella vinacea and had a maximum rate of 118 mumol sucralose/g dry weight cells/h, which was approximately 5% of the activity toward raffinose, and a K(m) of 5.8 mM toward TCR. The enzyme could be used in the form of mycelial pellets in a continuous packed bed column reactor. The reaction was also studied in a water-immiscible hydrophilic organic solvent, such as methyl isobutyl ketone, to overcome the poor aqueous solubility of TCR and to increase volumetric productivity. Synthesis of raffinose was achieved from saturated aqueous solutions of galactose and sucrose using a selected alpha-galactosidase from Aspergillus niger. When raffinose is used as a starting material for sucralose synthesis, this route has fewer steps than either the preceeding method using glucose-6-acetate as an intermediate or the complete chemical synthesis from sucrose. The relative merits of the two bioorganic routes and the utility of such methods to synthesize new sugars are discussed. 相似文献
18.
Synthetic building blocks bearing hydroxylated chiral centers are important targets for biocatalysis. Many C-C bond forming enzymes have recently been investigated for new applications and new strategies towards the synthesis of natural products and related oxygenated compounds. Several old catalysts have been studied to increase our functional knowledge of natural aldolase-type enzymes, and new mutated catalysts or catalytic antibodies have been tested for their synthetic utility. 相似文献
19.