Cells Of Candida Parapsilosis ATCC Research Articles

Understanding substrate specificity and enantioselectivity of carbonyl reductase from Candida parapsilosis ATCC 7330 (CpCR): Experimental and modeling studies

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.

Regio- and enantioselective reduction of diketones: preparation of enantiomerically pure hydroxy ketones catalysed by Candida parapsilosis ATCC 7330

Enantiomerically enriched hydroxy ketones were prepared by the reduction of the corresponding diketones with excellent enantiomeric excess (98%) and in good yields (up to 75%) using whole cells of Candida parapsilosis ATCC 7330. Cyclic diketones, such as 1,2-cyclohexanedione and 1,4-cyclohexanedione, resulted in hydroxy ketones as products. Cyclohexane-1,3-dione and 5,5-dimethylcyclohexane-1,3-dione gave dimerised products, such as 2,2′-(ethane-1,1-diyl)bis(3-hydroxycyclohex-2-enone) and 2,2′-(ethane-1,1-diyl)bis(3-hydroxy-5,5-dimethylcyclohex-2-enone) with acetaldehyde generated in situ from whole cells of Candida parapsilosis ATCC 7330, which is reported here for the first time.

ChemInform Abstract: Regio‐ and Enantio‐Selective Oxidation of Diols by Candida parapsilosis ATCC 7330.

Selectivity between primary and secondary alcohols was observed in oxidation using whole cells of Candida parapsilosis ATCC 7330, where the secondary alcohol was preferentially oxidized. In racemic sec alcohols, the ‘R’ enantiomer was selectively oxidized to the corresponding keto alcohol (yield = 18–54%) leaving the ‘S’ diol (yield = 31–69% and enantiomeric excess from 14% to >99%). A biphasic system consisting of isooctane–water (48 : 2 v/v) was used as a medium for biotransformation at 25 °C. This is the first report of the regio- and enantio-selective oxidation of diols using C. parapsilosis ATCC 7330.

Candida parapsilosis ATCC 7330 mediated oxidation of aromatic (activated) primary alcohols to aldehydes

A green, simple and high yielding [up to 86% yield] procedure is developed for the oxidation of aromatic (activated) primary alcohols to aldehydes using whole cells of Candida parapsilosis ATCC 7330.

ChemInform Abstract: Enantioselective Oxidation of Secondary Alcohols by Candida parapsilosis ATCC 7330.

Optically pure allylic alcohols and 4-phenylbutan-2-ols were prepared by oxidative kinetic resolution using whole cells of Candida parapsilosis ATCC 7330. Only the ‘S’ enantiomer is selectively oxidized to the corresponding keto compound (yield, 37–46%) leaving the ‘R’ alcohol (yield, 37–52% and ee 46 to >99%). The biocatalytic method is carried out under mild conditions at 20 °C, pH 6.5 in phosphate buffer.

Utilization of whole cell mediated deracemization in a chemoenzymatic synthesis of enantiomerically enriched polycyclic chromeno[4,3-b] pyrrolidines.

Various aryl and alkyl substituted optically pure propargyl alcohols were obtained with excellent ee (up to >99%) and isolated yields (up to 87%) by deracemization using whole cells of Candida parapsilosis ATCC 7330. The whole cells show substrate specificity towards alkyl substituted propargyl alcohols and a switch in the enantioselectivity has been observed from 'R' to 'S' upon increasing the chain length. For the first time, enantiopure (R)-4-(3-hydroxybut-1-ynyl)benzonitrile, (R)-4-(biphenyl-4-yl)but-3-yn-2-ol, (S)-ethyl 3-hydroxy-5-phenylpent-4-ynoate and (S)-4-phenylbut-3-yne-1,2-diol were obtained using this strategy. Optically pure propargyl alcohol thus obtained was used as a chiral starting material in the synthesis of enantiomerically enriched poly-substituted pyrrolidines and a pyrrole derivative successfully demonstrating a chemoenzymatic route.

Regio- and enantio-selective oxidation of diols by Candida parapsilosis ATCC 7330

Optically pure (S)-diols and their corresponding hydroxy ketones were prepared via regio- and enantio-selective oxidation of the corresponding diols using whole cells of Candida parapsilosis ATCC 7330.

A novel green route for the synthesis of N-phenylacetamides, benzimidazoles and acridinediones using Candida parapsilosis ATCC 7330

Biocatalytic preparation of various substituted N-phenylacetamides was carried out for the first time using whole cells of Candida parapsilosis ATCC 7330 under mild reaction conditions with excellent conversions (up to 93%) and good yields (up to 81%). Arylamine N-acetyltransferase (NAT) from whole cells of Candida parapsilosis ATCC 7330 is implicated in the N-acylation which is known to transfer the acetyl group from acetyl CoA (coenzyme A) to aromatic amines. Mechanistic investigation carried out using deuterated ethanol to find the source of acetyl CoA revealed that the reaction proceeds through the formation of acetaldehyde in situ, which is a potential source for the acetyl group of cytoplasmic acetyl CoA. Furthermore, experiments on regioselectivity, carried out with 2-phenylenediamine (2-PDA) resulted in a cyclised product 2-methyl benzimidazole (conversion 99%). The biocatalyst also mediates the cyclization of 3-(phenylamino)cyclohex-2-enones in the presence of the in situ generated acetaldehyde to form acridine-1,8-diones (conversion up to 70%), which is a green process reported here for the first time.

Biocatalytic reduction of α-keto amides to (R)-α-hydroxy amides using Candida parapsilosis ATCC 7330

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.

Resolution of N-protected amino acid esters using whole cells of Candida parapsilosis ATCC 7330

Whole cells of Candida parapsilosis ATCC 7330 were used for the resolution of N -acetyl amino acid esters. Excellent enantioselectivities ( E = 40 to >500) were achieved for the resolution of N-protected protein and non-protein amino acid esters giving good yields (28–50%) and high enantiomeric excesses (up to >99%) for both enantiomers.

Asymmetric synthesis of (S)-ethyl-4-chloro-3-hydroxybutanoate using Candida parapsilosis ATCC 7330

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.

Enantiomerically pure allylic alcohols: preparation by Candida parapsilosis ATCC 7330 mediated deracemisation

Biocatalytic deracemisation of racemic allylic alcohols by whole cells of Candida parapsilosis ATCC 7330 resulted in the formation of the ( R)-enantiomers in high enantiomeric excesses (up to >99%) and isolated yields (up to 79%).

Preparation of optically pure alkyl 3-(hetero-2-yl)-3-hydroxypropanoates by Candida parapsilosis ATCC 7330 mediated deracemisation

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%).

Deracemisation of β-hydroxy esters using immobilised whole cells of Candida parapsilosis ATCC 7330: substrate specificity and mechanistic investigation

Deracemisation of aryl substituted β-hydroxy esters by immobilised whole cells of Candida parapsilosis ATCC 7330 gave >99% ee and up to 75% yield of their corresponding ( S)-enantiomers. Mechanistic investigation of the deracemisation reaction carried out using a deuterated substrate, ethyl 3-deutero-3-hydroxy-3-phenyl propanoate revealed that while the ( S)-enantiomer remains unreacted the ( R)-enantiomer undergoes enantioselective oxidation to its corresponding ketoester, which on complementary enantiospecific reduction gives the ( S)-enantiomer in high yield and % ee.

Deracemisation of aromatic β-hydroxy esters using immobilised whole cells of Candida parapsilosis ATCC 7330 and determination of absolute configuration by 1H NMR

Deracemisation of aryl and substituted aryl β-hydroxy esters using immobilised whole cells of Candida parapsilosis ATCC 7330 yields the corresponding ( S)-enantiomer in >99% enantiomeric excess and good yield (up to 68%). The absolute configuration of ethyl 3-(2,4-dichlorophenyl)-3-hydroxy propanoate and ethyl 3-hydroxy-5-phenyl-pent-4-enoate as determined by 1H NMR using MTPA chloride was found to be ‘ S’. The chemical shifts of the methoxy groups of the two diastereomeric MTPA esters were used as diagnostic signals to determine the absolute configuration.