Microbial deracemisation of aromatic β-hydroxy acid esters

A carbonyl reductase from Candida parapsilosis ATCC 7330: substrate selectivity and enantiospecificity

A purified carbonyl reductase (SRED) asymmetrically reduces ketones and α-ketoesters to (S)-alcohols with a potential application in the synthesis of industrially important chiral molecules.

A fourier transform infrared spectroscopy (FTIR) based assay for Candida parapsilosis ATCC 7330 mediated oxidation of aryl alcohols

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 R(2)≥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.

Unexpected Stereorecognition in Nitrilase-Catalyzed Hydrolysis of β-Hydroxy Nitriles

Biocatalytic enantioselective hydrolysis of beta-hydroxy nitriles to corresponding (S)-enriched beta-hydroxy carboxylic acids has been achieved for the first time by an isolated nitrilase bll6402 from Bradyrhizobium japonicum USDA110. This offers a new "green" approach to optically pure beta-hydroxy nitriles and beta-hydroxy carboxylic acids. The observed remote stereorecognition is surprising because this nitrilase shows no enantioselectivity for the hydrolysis of alpha-hydroxy nitriles such as mandelonitrile.

Dramatic Enhancement of Enantioselectivity of Biotransformations of β-Hydroxy Nitriles Using a Simple O-Benzyl Protection/Docking Group

[Structure: see text] Catalyzed by the Rhodococcus erythropolis AJ270 whole cell catalyst, the O-benzylated beta-hydroxy alkanenitriles underwent remarkably high enantioselective biotransformations, whereas the biotransformations of free beta-hydroxy alkanenitriles gave very low enantioselectivity. The easy manipulations of O-protection and O-deprotection, excellent chemical and enantiomeric yields of biotransformations, along with the scalability render this enzymatic transformation attractive and practical for the synthesis of highly enantiopure beta-hydroxy alkanoic acids and their amide derivatives.