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Anju Chadha
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Anju Chadha
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Anju Chadha
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Chadha, A.
Chadha, Anju
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7 results
Now showing 1 - 7 of 7
- PublicationWhole Cells Mediated Biocatalytic Reduction of Alpha-Keto Esters: Preparation of Optically Enriched Alkyl 2-hydroxypropanoates(20-06-2022)
;Venkataraman, SowmyalakshmiBiocatalytic reduction of alkyl 2-oxopropanoates were carried out by utilizing the whole cells of Candida parapsilosis ATCC 7330 to form the optically enriched alkyl 2-hydroxypropanoates with good enantiomeric excess (ee) (≤91%) and isolated yields (≤68%). Enantiomerically enriched (S)-ethyl 3-bromo-2-hydroxypropanoate thus synthesized by biocatalytic reduction of ethyl 3-bromo-2-oxopropanoate is presented in this study for the first time in water under ambient reaction conditions in a reaction time of 4 h which is considerably less than earlier reported procedures. - PublicationCandida parapsilosis: A versatile biocatalyst for organic oxidation-reduction reactions(01-10-2016)
; ;Venkataraman, Sowmyalakshmi ;Preetha, RadhakrishnanPadhi, Santosh KumarThis review highlights the importance of the biocatalyst, Candida parapsilosis for oxidation and reduction reactions of organic compounds and establishes its versatility to generate a variety of chiral synthons. Appropriately designed reactions using C. parapsilosis effect efficient catalysis of organic transformations such as deracemization, enantioselective reduction of prochiral ketones, imines, and kinetic resolution of racemic alcohols via selective oxidation. This review includes the details of these biotransformations, catalyzed by whole cells (wild type and recombinant strains), purified enzymes (oxidoreductases) and immobilized whole cells of C. parapsilosis. The review presents a bioorganic perspective as it discusses the chemo, regio and stereoselectivity of the biocatalyst along with the structure of the substrates and optical purity of the products. Fermentation scale biocatalysis using whole cells of C. parapsilosis for several biotransformations to synthesize important chiral synthons/industrial chemicals is included. A comparison of C. parapsilosis with other whole cell biocatalysts for biocatalytic deracemization and asymmetric reduction of carbonyl and imine groups in the synthesis of a variety of enantiopure products is presented which will provide a basis for the choice of a biocatalyst for a desired organic transformation. Thus, a wholesome perspective on the present status of C. parapsilosis mediated organic transformations and design of new reactions which can be considered for large scale operations is provided. Taken together, C. parapsilosis can now be considered a ‘reagent’ for the organic transformations discussed here. - PublicationAsymmetric reduction of alkyl-3-oxobutanoates by Candida parapsilosis ATCC 7330: Insights into solvent and substrate optimisation of the biocatalytic reaction(01-10-2013)
;Venkataraman, Sowmyalakshmi ;Roy, Rony K.Asymmetric reduction of alkyl-3-oxobutanoates mediated by Candida parapsilosis ATCC 7330 resulted in optically pure alkyl-3-hydroxybutanoates in good yields (up to 72 %) and excellent enantiomeric excess (up to >99 %). A detailed and systematic optimisation study was necessary and was carried out to avoid the undesired transesterification reaction during the course of asymmetric reduction. Under optimised conditions, the (S)-alkyl hydroxyesters were produced predominantly except for the methyl ester which formed the (R)-enantiomer. To the best of our knowledge, the biocatalytic asymmetric reduction of isoamyl-3-oxobutanoate to (S)-isoamyl-3-hydroxybutanoate is reported here for the first time. © 2013 Springer Science+Business Media New York. - PublicationHighly stereoselective reduction of 4-Aryl-2-oxo but-3-enoic carboxylic esters by plant cell culture of Daucus carota(02-01-2004)
;Baskar, B. ;Ganesh, Sujatha ;Lokeswari, T. S.A highly enantioselective preparation (92-99% enantiomeric excess, 100% conversion) of various 4-aryl-2-hydroxy but-3-enoic carboxylic acid esters from the corresponding 4-phenyl-2-keto but-3-enoic acid esters mediated by plant cell cultures of Daucus carota under mild and environmentally benign conditions in aqueous medium is described. © 2003 Elsevier B.V. All rights reserved. - PublicationPurification and characterisation of (S)-specific alcohol dehydrogenase from Candida parapsilosis ATCC 7330(01-04-2022)
;Pinto, Jerrina; Alcohol dehydrogenases (ADHs) catalyses reversible reduction of carbonyl group to its corresponding alcohols and have been widely employed as versatile biocatalyst due to its high enantioselectivity to produce chiral alcohols. In this study, the (S) - specific alcohol dehydrogenase (S-ADH) enzyme was purified from Candida parapsilosis ATCC 7330. It asymmetrically reduced acetophenone to (S)-1-phenylethanol with > 99% ee with an effective substrate coupled approach for cofactor recycling. In the reverse reaction, i.e., oxidation of 1-phenylethanol, S-ADH produced (R)-1-phenylethanol with > 99% ee via kinetic resolution. S-ADH is a zinc dependent medium chain dehydrogenase/reductase. It was found to be a tetramer in nature with subunit molecular mass of 40 kDa catalysing oxidation and reduction reactions only using NAD+ and NADH as the cofactors respectively with higher affinity for NAD+. Further biochemical characterisation indicated that His and Cys residues play a crucial role in the enzymatic catalysis and requires a reducing environment at the active site. S-ADH was stable at pH 6.0 in reducing acetophenone and pH 8.0 in oxidising 1-phenylethanol at 45 °C with the t1/2 of 6.8 h and 9.0 h respectively. Therefore, purified S-ADH would be a useful biocatalyst in the synthesis of enantiopure (S)- and (R)-1-phenylethanol which are used in the fragrance preparation. - PublicationPreparation of enantiomerically enriched (S)-ethyl 3-hydroxy 4,4,4-trifluorobutanoate using whole cells of Candida parapsilosis ATCC 7330(01-01-2015)
;Venkataraman, SowmyalakshmiOptically pure (S)-ethyl 3-hydroxy 4,4,4-trifluorobutanoate was prepared using the biocatalyst Candida parapsilosis ATCC 7330 by deracemisation of the racemic alcohol ester in high optical purity (96%) and yield (65%) and by asymmetric reduction from its prochiral ketone (ee up to 84% and yield 60%) under different reaction conditions. This study highlights the possibility of using the same biocatalyst to produce (S)-ethyl 3-hydroxy 4,4,4-trifluorobutanoate using different strategies. - PublicationAsymmetric synthesis of (S)-ethyl-4-chloro-3-hydroxybutanoate using Candida parapsilosis ATCC 7330(01-02-2010)
;Kaliaperumal, Tarjan ;Kumar, S.; Asymmetric reduction of ethyl-4-chloro-3-oxobutanoate to (S)-ethyl-4-chloro-3-hydroxybutanoate in aqueous medium by resting cells of Candida parapsilosis ATCC 7330 was optimized. The influence of culture parameters (inoculum size, inoculum age and biocatalyst harvest time) and reaction parameters (co-substrate, resting cell, pH and substrate concentrations) on the asymmetric reduction were studied. It was found that these parameters significantly influenced the rate of the asymmetric reduction. Under the optimum conditions, the final concentration of (S)-ethyl-4-chloro-3- hydroxybutanoate, enantiomeric excess and the isolated yield of (S)-ethyl-4-chloro-3-hydroxybutanoate were 1.38 M (230 g/l), >99 and 95%, respectively. The space time yield was 115 mmol/lh, which is significantly higher than other whole cell biocatalysts reported so far. © 2009 Society for Industrial Microbiology.