Nanwei Wan

Synthesis of superparamagnetic carboxymethyl chitosan/sodium alginate nanosphere and its application for immobilizing α-amylase

In order to improve catalytic activity, increase recycling times, reduce use cost for enzyme, superparamagnetic carboxymethyl chitosan/sodium alginate nanosphere (SM/CMC/SA) has been synthesized via an improved hydrothermal method, molecular self-assembly technology, electrostatic interaction and amide linkage. Its mean diameter was 65nm, zeta potential was -36.9mV and BET was 53.8m(2)/g. α-Amylase was selected as a simulation object to manufacture an immobilized enzyme (SM/CMC/CA/α-Amy), and its catalytic activity, release behavior, reusability and stability were researched. Immobilization increased 4.67 times to catalytic activity, slowed down release rate and improved reusable performance. SM/CMC/CA/α-Amy showed higher activity over a wider pH range, especially in strong acidic and alkaline environments. The thermal stability and storage stability were improved remarkably too. All these results indicated that SM/CMC/SA was an ideal carrier for immobilizing enzyme.

Biocatalytic α-Oxidation of Cyclic Amines and N-Methylanilines for the Synthesis of Lactams and Formamides

An environmentally friendly method for the synthesis of lactams and formamides through the biocatalytic α‐oxidation of amines was developed by employing Pseudomonas plecoglossicida ZMU‐T04 as a biocatalyst. In this biocatalytic process, the α‐oxidation of cyclic amines and N‐methylanilines proceeded smoothly to give the corresponding amides in low to high yields. Furthermore, it was demonstrated that synthetic 3,4‐dihydroquinolin‐2(1H)‐one could be used as a key precursor of antidepressant bioactive molecules. The mechanism of this biocatalytic α‐oxidation process was investigated by isotope‐ labeling experiments.

A Protocol for the Synthesis of CF2H-Containing Pyrazolo[1,5-c]quinazolines from 3-Ylideneoxindoles and in Situ Generated CF2HCHN2

Herein is disclosed a selective and facile approach for the construction of CF2H-containing pyrazolo[1,5- c]quinazolines from easily accessible 3-ylideneoxindoles and in situ generated CF2HCHN2. The reaction involving a [3 + 2] cycloaddition/1,3-H shift/rearrangement/dehydrogenation cascade proceeded smoothly at room temperature in the absence of catalyst and additive. Moreover, this metal-free process along with mild conditions is desirable and valuable for the pharmaceutical industry. Importantly, this reaction features a broad substrate scope, good functional group tolerance, and gram-scale synthesis.

Biocatalytical asymmetric sulfoxidation by identifying cytochrome P450 from Parvibaculum lavamentivorans DS-1

Cytochrome P450 monooxygenases (P450s) catalyzed asymmetric sulfoxidation represents a green route for the synthesis of valuable enantiopure sulfoxides, which are potentially interesting synthons in synthetic and pharmaceutical chemistry. Here the potential P450 and redox partner genes from Parvibaculum lavamentivorans DS‐1 are screened and co‐expressed in Escherichia coli host to construct twenty recombinant P450 strains. By testing the whole‐cell biooxidation of thioanisole, P450PL2 (CYP278A4) and P450PL7 (CYP108G3) are identified with excellent S enantioselectivity while P450PL1 (CYP111B1) and P450PL9 (CYP153A26) exhibit the complementary R enantioselectivity. Asymmetric sulfoxidation of sulfides 1 a–1 m is further investigated using the recombinant E. coli strain P450PL2‐2 based on the optimal conditions, producing the corresponding enantioenriched sulfoxides with up to 82 % isolated yield and 99 % ee.

Deracemization of Phenyl-Substituted 2-Methyl-1,2,3,4-Tetrahydroquinolines by a Recombinant Monoamine Oxidase from Pseudomonas monteilii ZMU-T01

A monoamine oxidase (MAO5) from Pseudomonas monteilii ZMU‐T01 was first heterologously expressed in Escherichia coli BL21(DE3) and then used as a biocatalyst for the deracemization of racemic 2‐methyl‐1,2,3,4‐tetrahdroquinoline derivatives to yield the unreacted R enantiomer with up to >99 % ee. Sequence alignment revealed that MAO5 shared 14.7 % identity toward the well‐studied monoamine oxidase (MAO‐N).

Identification and characterization of a highly S-enantioselective halohydrin dehalogenase from Tsukamurella sp. 1534 for kinetic resolution of halohydrins

Halohydrin dehalogenases are remarkable enzymes which possess promiscuous catalytic activity and serve as potential biocatalysts for the synthesis of chiral halohydrins, epoxides and β-substituted alcohols. The enzyme HheC exhibits a highly R enantioselectivity in the processes of dehalogenation of vicinal halohydrins and ring-opening of epoxides, which attracts more attentions in organic synthesis. Recently dozens of novel potential halohydrin dehalogenases have been identified by gene mining, however, most of the characterized enzymes showed low stereoselectivity. In this study, a novel halohydrin dehalogenase of HheA10 from Tsukamurella sp. 1534 has been heterologously expressed, purified and characterized. Substrate spectrum and kinetic resolution studies indicated the HheA10 was a highly S enantioselective enzyme toward several halohydrins, which produced the corresponding epoxides with the ee (enantiomeric excess) and E values up to >99% and >200 respectively. Our results revealed the HheA10 was a promising biocatalyst for the synthesis of enantiopure aromatic halohydrins and epoxides via enzymatic kinetic resolution of racemic halohydrins. Whats more important, the HheA10 as the first individual halohydrin dehalogenase with the highly S enantioselectivity provides a complementary enantioselectivity to the HheC.