Now showing 1 - 10 of 11
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    A fourier transform infrared spectroscopy (FTIR) based assay for Candida parapsilosis ATCC 7330 mediated oxidation of aryl alcohols
    (19-06-2015)
    Sudhakara, Sneha
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    We present an FTIR based assay to monitor the whole cell mediated oxidation of aryl alcohols by measuring the characteristic IR absorption of the hydroxyl group [OH] of the substrate and the carbonyl group [CO] of the corresponding oxidized product. This method expedites the analysis of whole cell mediated catalysis which is usually done by GC and/or HPLC. The FTIR assay had linearity with R2≥0.980 and sensitivity up to 10μM. The accuracy and precision of FTIR assay was found ≥81% and ≥94%, respectively. This assay was validated by GC which exhibited ≥82% accuracy and ≥79% precision. The time of analysis taken by this assay was 2-3min per sample in comparison with 20-40min by GC.
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    Biocatalytic deracemisation of aliphatic β-hydroxy esters: Improving the enantioselectivity by optimisation of reaction parameters
    (01-02-2015)
    Venkataraman, Sowmyalakshmi
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    Optically pure aliphatic β-hydroxy esters were prepared from their racemates by deracemisation using the biocatalyst Candida parapsilosis ATCC 7330. High optical purity (up to >99 %) and good yields (up to 71 %) of the product secondary alcohols were obtained. This study highlights the importance of optimization of reaction conditions using ethyl-3-hydroxybutanoate as the model substrate to improve the enantioselectivity (enantiomeric excess from 9 to 98 %). The present study emphasises the broad substrate scope of the biocatalyst towards deracemisation. This is the first report of Candida parapsilosis ATCC 7330-mediated deracemisation of various alkyl-3-hydroxybutanoates to produce either the (R)-enantiomers (methyl, ethyl, propyl, butyl, t-butyl, allyl-3-hydroxybutanoates) or (S)-enantiomers (pentyl, iso-amyl and iso-propyl-3-hydroxybutanoates).
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    Whole resting cells vs. cell free extracts of Candida parapsilosis ATCC 7330 for the synthesis of gold nanoparticles
    (01-12-2016)
    Krishnan, Saravanan
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    Narayan, Shoba
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    The cell free extracts of Candida parapsilosis ATCC 7330 are more efficient than the whole resting cells of the yeast in the synthesis of directly usable gold nanoparticles as revealed by this systematic study. Cell free extracts yielded gold nanoparticles of hydrodynamic diameter (50–200 nm). In this study, the total protein concentration influences the nanofabrication and not only the reductase enzymes as originally thought. Powder X-ray diffraction studies confirm the crystalline nature of the gold nanoparticles. Fourier Transform Infra Red spectroscopy and thermal gravimetric analysis suggests that the biosynthesized gold nanoparticles are capped by peptides/proteins. Dispersion experiments indicate a stable dispersion of gold nanoparticles in pH 12 solutions which is also confirmed by electron microscopic analysis and validated using a surface plasmon resonance assay. The effectiveness of the dispersed nanoparticles for the reduction of 4-nitrophenol using sodium borohydride as a reductant further confirms the formation of functional gold nanoparticles. It is also reported that gold nanoparticles with mean particle diameter of 27 nm are biosynthesized inside the whole cell by transmission electron microscopy analysis. With optimized reaction conditions, maximum gold bioaccumulation with the 24 h culture age of the yeast with cellular uptake of ~1010 gold atoms at the single cell level is achieved but it is not easy to extract the gold nanoparticles from the whole resting cells.
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    Deracemisation of aryl substituted α-hydroxy esters using Candida parapsilosis ATCC 7330: Effect of substrate structure and mechanism
    (26-12-2005)
    Baskar, B.
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    Pandian, N. G.
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    Priya, K.
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    Candida parapsilosis ATCC 7330 was found to be an efficient biocatalyst for the deracemisation of aryl α-hydroxy esters (65-85% yield and 90-99% ee). A variety of aryl and aryl substituted α-hydroxy esters were synthesized to reflect steric and electronic effects on biocatalytic deracemisation. The mechanism of this biocatalytic deracemisation was found to be stereoinversion. © 2005 Elsevier Ltd. All rights reserved.
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    Asymmetric 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
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    Roy, Rony K.
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    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.
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    Understanding substrate specificity and enantioselectivity of carbonyl reductase from Candida parapsilosis ATCC 7330 (CpCR): Experimental and modeling studies
    (01-12-2018)
    Aggarwal, Nidhi
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    Ananthathamula, Ragamanvitha
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    Karanam, Vinay Kumar
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    The whole cells of Candida parapsilosis ATCC 7330 are a well-established biocatalyst used for oxidation and reduction of various organic compounds to generate chiral synthons. Recombinantly expressed carbonyl reductase (CpCR) from the same strain reduces aryl α–ketoesters to their respective optically pure alcohols but preferentially reduces aliphatic and aryl aldehydes to primary alcohols. The prochiral substrates viz. aryl α-ketoester [Ethyl-2-oxo-4-phenylbutanoate], aryl ketone [Acetophenone] and aliphatic β-ketoester [Ethyl-4,4,4-trifloro-3-oxo-butanoate] get reduced to (R)-alcohols with CpCR while an aryl ketoaldehyde [2-oxo-2-phenylacetaldehyde] gives the (S)-alcohol. The optimal orientation required for the high conversion and desired enantioselectivity was analyzed by docking the α/β ketoesters, ketoaldehyde and a ketone with a modeled CpCR. Aryl α-ketoester, having the lowest free energy (-8.43 kcal/mol), shows the most favorable binding with CpCR (Interaction Energy = 7.9 kcal/mol). Also, the close proximity of aryl α-ketoester to the cofactor NADPH (2.82 Å) facilitates a better Pro-R hydride transfer as compared to other substrates.
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    Candida parapsilosis ATCC 7330 can also deracemise 1-arylethanols
    (01-12-2011)
    Kaliaperumal, Tarjan
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    Candida parapsilosis ATCC 7330 grown using different culture conditions (inoculum size 4% (v/v), inoculum age 12 h, and harvest time 14 h) from those previously reported (inoculum size 2% (v/v), inoculum age 24 h, and harvest time 44 h) successfully deracemised racemic 1-arylethanols and 4-phenyl-2-butanol to the (R)-enantiomer (ee up to >99%). The deracemisation of racemic 1-aryl ethanol proceeds via (i) enantioselective oxidation of (S)-enantiomer followed by (ii) reduction of the ketone formed to give the racemic alcohol which gets kinetically resolved thus enriching for the (R)-enantiomer from the racemate. This is the first report on the deracemisation of 1-arylethanols using Candida parapsilosis ATTC 7330 via dynamic kinetic resolution. © 2011 Informa UK, Ltd.
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    Preparation of optically pure alkyl 3-(hetero-2-yl)-3-hydroxypropanoates by Candida parapsilosis ATCC 7330 mediated deracemisation
    (01-06-2008)
    Titu, D.
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    Deracemisation of racemic alkyl 3-(hetero-2-yl)-3-hydroxypropanoates using whole cells of Candida parapsilosis ATCC 7330 resulted in the formation of the 'S' enantiomer in high enantiomeric excess (up to >99% ee) and isolated yields (up to 75%). © 2007 Elsevier B.V. All rights reserved.
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    Biocatalytic reduction of α-keto amides to (R)-α-hydroxy amides using Candida parapsilosis ATCC 7330
    (30-12-2012)
    Stella, Selvaraj
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    Biocatalytic reduction of primary and secondary α-keto amides was accomplished using whole cells of Candida parapsilosis ATCC 7330. The primary (R)-α-hydroxy amides were obtained in good enantiomeric excess (up to 94%) and conversion (88-99%) as compared to the secondary (R)-α-hydroxy amides. © 2012 Elsevier B.V.
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    Preparation of enantiomerically enriched (S)-ethyl 3-hydroxy 4,4,4-trifluorobutanoate using whole cells of Candida parapsilosis ATCC 7330
    (01-01-2015)
    Venkataraman, Sowmyalakshmi
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    Optically 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.