Enzymatic resolution of substituted mandelic acids

Covalent Immobilization of Candida rugosa Lipase on Epichlorohydrin-Coated Magnetite Nanoparticles: Enantioselective Hydrolysis Studies of Some Racemic Esters and HPLC Analysis

In this study, a new biocatalyst was prepared by immobilizing Candida rugosa lipase epichlorohydrin-functionalized onto the surface of the nanoparticles. Magnetite nanoparticles were obtained by chemical co-precipitation method of Fe²⁺ and Fe³⁺, and then the prepared uncoated and coated nanoparticles were characterized by XRD, FT-IR and TGA. Lipase was covalently attached to activated nanoparticles. The catalytic properties of free and immobilized lipases were determined. It was found that the optimum temperature for free and immobilized lipases was 30 °C and 35 °C, respectively. The optimum pH values were found to be 7.0 and 8 for free and immobilized lipases, respectively. Immobilized lipase was found to retain significant activity even after the seventh use. In the final section of the study, optically pure compounds were obtained by carrying out the enantioselective hydrolysis studies of racemic esters by using immobilized lipase. Enantiomeric excesses of the products in the enantioselective hydrolysis of racemic ibuprofen and naproxen methyl ester and racemic butyl mandelate were determined to be 94.93, 77.30 and 68.15, respectively.

Enantioselective cascade biocatalysis for deracemization of 2-hydroxy acids using a three-enzyme system

Background

Enantiopure 2-hydroxy acids are key intermediates for the synthesis of pharmaceuticals and fine chemicals. We present an enantioselective cascade biocatalysis using recombinant microbial cells for deracemization of racemic 2-hydroxy acids that allows for efficient production of enantiopure 2-hydroxy acids.

Results

The method was realized by a single recombinant Escherichia coli strain coexpressing three enzymes: (S)-2-hydroxy acid dehydrogenase, (R)-2-keto acid reductase and glucose dehydrogenase. One enantiomer [(S)-2-hydroxy acid] is firstly oxidized to the keto acid with (S)-2-hydroxy acid dehydrogenase, while the other enantiomer [(R)-2-hydroxy acid] remains unchanged. Then, the keto acid obtained reduced to the opposite enantiomer with (R)-2-keto acid reductase plus cofactor regeneration enzyme glucose dehydrogenase subsequently. The recombinant E. coli strain coexpressing the three enzymes was proven to be a promising biocatalyst for the cascade bioconversion of a structurally diverse range of racemic 2-hydroxy acids, giving the corresponding (R)-2-hydroxy acids in up to 98.5 % conversion and >99 % enantiomeric excess.

Conclusions

In summary, a cascade biocatalysis was successfully developed to prepare valuable (R)-2-hydroxy acids with an efficient three-enzyme system. The developed elegant cascade biocatalysis possesses high atom efficiency and represents a promising strategy for production of highly valued (R)-2-hydroxy acids.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-016-0560-1) contains supplementary material, which is available to authorized users.

A chemoselective oxidation of monosubstituted ethylene glycol: facile synthesis of optically active α-hydroxy acids

A mild and efficient method for the chemoselective oxidation of monosubstituted ethylene glycols to optically active α-hydroxy acids has been achieved using the TEMPO–NaOCl reagent system.

A thermostable and organic-solvent tolerant esterase from Pseudomonas putida ECU1011: catalytic properties and performance in kinetic resolution of α-hydroxy acids

A novel esterase, rPPE01, from Pseudomonas putida ECU1011 was heterologously expressed in Escherichia coli and identified for enzymatic resolution of hydroxy acids via O-deacetylation. α-Acetoxy carboxylates were converted with approximately 50% yield and excellent enantioselectivity (E>200) at a substrate concentration of 100 mM. The half-lives of rPPE01 were 14 days at 50°C and 30 days at 30°C, indicating the enzyme has relatively high thermostability. Another remarkable advantage of rPPE01 is that both the activity and thermostability were enhanced significantly in the presence of hydrophobic alkanes and ethers. rPPE01 retained 159% of its initial activity after incubation with 50% (v/v) n-heptane at 30°C for 60 days. The attractive organic-solvent tolerance, good thermostability and high enantioselectivity towards α-acetoxy carboxylates endow rPPE01 with the potential of practical application for the production of enantiopure hydroxy acids.

Design, asymmetric synthesis, and evaluation of pseudosymmetric sulfoximine inhibitors against HIV-1 protease

The HIV-1 protease is a validated drug target for the design of antiretroviral drugs to combat AIDS. We previously established the sulfoximine functionality as a valid transition state mimetic (TSM) in the HIV-1 protease inhibitors (PI) design and have identified a lead pseudosymmetric compound with nanomolar enzymatic inhibitory activity. Here, we report the asymmetric synthesis of this compound and its application in the synthesis of sulfoximine-based peptidomimetic HIV-1 protease inhibitors. Molecular modeling revealed the potential mode of binding of the sulfoximine inhibitor as a TSM. The predicted absolute binding free energies suggested similar inhibitory effect as observed in our enzymatic inhibitory studies.

Enantioselective alpha-hydroxylation of 2-arylacetic acid derivatives and buspirone catalyzed by engineered cytochrome P450 BM-3

Here we report that an engineered microbial cytochrome P450 BM-3 (CYP102A subfamily) efficiently catalyzes the alpha-hydroxylation of phenylacetic acid esters. This P450 BM-3 variant also produces the authentic human metabolite of buspirone, R-6-hydroxybuspirone, with 99.5% ee.