Activity and specificity studies of the new thermostable esterase EstDZ2.

In this paper, we study the activity and specificity of EstDZ2, a new thermostable carboxyl esterase of unknown function, which was isolated from a metagenome library from a Russian hot spring. The biocatalytic reaction employing EstDZ2 proved to be an efficient method for the hydrolysis of aryl p-, o- or m-substituted esters of butyric acid and esters of secondary alcohols. Docking studies revealed structural features of the enzyme that led to activity differences among the different substrates.

An Efficient Chemoenzymatic Approach towards the Synthesis of Rugulactone.

Rugulactone is a natural product isolated from the plant . It has shown very important biological activity as an inhibitor of the nuclear factor κB (NF-κB) activation pathway. A new chemoenzymatic approach towards the synthesis of rugulactone is presented here.

Oxone-mediated oxidative cleavage of β-keto esters and 1,3-diketones to α-keto esters and 1,2-diketones in aqueous medium.

A versatile and highly efficient method for the direct synthesis of α-keto esters and 1,2-diketones has been developed. This approach utilizes the oxidative cleavage of a variety of β-keto esters and 1,3-diketones mediated by an Oxone/aluminum trichloride system. The simple one-step oxidation reaction proceeded selectively in aqueous media to afford products in high yields, short reaction times, and environmentally benign conditions.

Enzymatic reductions for the regio- and stereoselective synthesis of hydroxy-keto esters and dihydroxy esters.

Ketoreductases were utilized for the stereoselective synthesis of δ-hydroxy-β-keto esters, β-hydroxy-δ-keto esters, and β,δ-dihydroxy esters. Seven out of eight possible stereoisomers were obtained from the enzymatic reduction of the corresponding β,δ-diketo ester in high enantio- and diastereomeric excess.

A two-step, one-pot enzymatic synthesis of 2-substituted 1,3-diols.

A biocatalytic cascade reaction was designed for the stereoselective synthesis of optically pure 2-alkyl-1,3-diols employing two enzymes. The cascade process consists of two consecutive steps: a stereoselective diketone reduction and a hydroxy ketone reduction. Chiral diols were formed by the addition of ketoreductases in the same vessel, in high stereoselectivity and chemical yield, without the isolation of the intermediate β-hydroxy ketones.

A convenient method for the assignment of relative configuration of acyclic alpha-alkyl-beta-hydroxy carbonyl compounds by (1)H NMR.

The relative configuration of acyclic alpha-alkyl-beta-hydroxy carbonyl compounds can be determined by using (1)H NMR spectroscopy. The assignment can be achieved by recording the (1)H NMR spectrum of the syn-anti mixture. The upfield carbinol hydrogen signal belongs to the anti whereas the downfield to the syn stereoisomer.

Highly stereoselective reductions of alpha-alkyl-1,3-diketones and alpha-alkyl-beta-keto esters catalyzed by isolated NADPH-dependent ketoreductases.

[reaction: see text] The biocatalytic reduction of alpha-alkyl-1,3-diketones and alpha-alkyl-beta-keto esters employing 1 of 20 different isolated NADPH-dependent ketoreductases proved to be a highly efficient method for the preparation of optically pure keto alcohols or hydroxy esters.

Asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens.

A new asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens has been found. Although alcohols are not the natural substrates for this enzyme, a high R enantioselectivity was observed. Stereochemical studies showed that variations in substrate structure lead to strong variations in enantioselectivity.