Tianxi Zhang
Jiangsu University
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Featured researches published by Tianxi Zhang.
Medicinal Chemistry Research | 2014
Huayou Chen; Tengyun Sun; Hongzhang Chen; Rui Tian; Tianxi Zhang; Zhi Chen; Zhong Ni
The monoacylglycerol lipase (MAGL) regulates 2-arachidonoyl glycerol (2-AG) level in the endocannabinoid system (ECS), which is implicated in a number of severe diseases such as cancer and Alzheimer’s disease. However, most existing MAGL inhibitors also show additional inhibitory effects on fatty acid amide hydrolase (FAAH), another member of the ECS that degrades the 2-AG analog N-arachidonoyl ethanolamine. Understanding of molecular mechanism and biological implication underlying the specific interactions in MAGL–ligand recognition is thus fundamentally important for the rational design of selective MAGL inhibitors. In the current study, the structural basis and energetic property regarding the binding of several MAGL inhibitors as well as its substrate 2-AG to both the MAGL and FAAH are investigated systematically by integrating molecular docking, quantum mechanics/molecular mechanics analysis, and Poisson–Boltzmann/surface area solvent model. In addition, a novel quantitative structure–selectivity relationship method is proposed to help in the explanation and prediction of inhibitor selectivity between MAGL and FAAH. It is suggested that the selectivity is primarily determined by the size, topology, and property of the rear moiety of inhibitor compounds; a bulky, bifurcated rear is the prerequisite for a inhibitor to have high selectivity for MAGL over FAAH, whereas those dual-type MAGL–FAAH inhibitors should possess a small, rear moiety—the ideal choice is a single aromatic branch occupying this position.
Journal of Molecular Microbiology and Biotechnology | 2015
Huayou Chen; Tianxi Zhang; Tengyun Sun; Zhong Ni; Yilin Le; Rui Tian; Zhi Chen; Chunxia Zhang
Nitrilases are an important class of industrial enzymes. They require mild reaction conditions and are highly efficient and environmentally friendly, so they are used to catalyze the synthesis of carboxylic acid from nitrile, a process considered superior to conventional chemical syntheses. Nitrilases should be immobilized to overcome difficulties in recovery after the reaction and to stabilize the free enzyme. The nitrilase from Clostridium thermocellum was expressed, identified and displayed on the surface of Bacillus subtilis spores by using the spore coat protein G of B. subtilis as an anchoring motif. In a free state, the recombinant nitrilase catalyzed the conversion of 3-cyanopyridine to niacin and displayed maximum catalytic activity (8.22 units/mg protein) at 40°C and pH 7.4. SDS-PAGE and Western blot were used to confirm nitrilase display. Compared with the free enzyme, the spore-immobilized nitrilase showed a higher tolerance for adverse environmental conditions. After the reaction, recombinant spores were recovered via centrifugation and reused 3 times to catalyze the conversion of 3-cyanopyridine with 75.3% nitrilase activity. This study demonstrates an effective means of nitrilase immobilization via spore surface display, which can be applied in biological processes or conversion.
Journal of Molecular Microbiology and Biotechnology | 2017
Huayou Chen; Zhi Chen; Bangguo Wu; Jawad Ullah; Tianxi Zhang; Jinru Jia; Hongcheng Wang; Tianwei Tan
In the present study, fusion genes composed of Thermotoga maritima MSB8 nitrilase and Bacillus subtilis 168 outer coat protein CotG were constructed with various peptide linkers and displayed on B. subtilis DB 403 spores. The successful display of CotG-nit fusion proteins on the spore surface of B. subtilis was verified by Western blot analysis and activity measurement. It was demonstrated that the fusion with linker GGGGSEAAAKGGGGS presented the highest thermal and pH stability, which is 2.67- and 1.9-fold of the fusion without linker. In addition, fusion with flexible linker (GGGGS)3 demonstrated better thermal and pH stability than fusions with linkers GGGGS and (GGGGS)2. Fusion with rigid linker (EAAAK) demonstrated better thermal stability than fusions with linkers (EAAAK)2 and (EAAAK)3. Fusions with linker (EAAAK)2 demonstrated better pH stability than fusions with linkers (EAAAK) and (EAAAK)3. In the presence of 1 mM dithiothreitol, 1% (v/v) sodium dodecyl sulfate, and 20% (v/v) ethanol, the optimal linkers of the fusions were MGSSSN, GGGGSEAAAKGGGGS, and (GGGGS)3, respectively. In summary, our results showed that optimizing the peptide linkers with different type, length, and amino acid composition of the fusion proteins would be an efficient way to maintain the stability of fusion proteins and thus improve the nitrilase display efficiency, which could provide an effective method for rational design peptide linkers of displayed nitrilase on B. subtilis.
Journal of Microbiology and Biotechnology | 2015
Zhi Chen; Huayou Chen; Zhong Ni; Rui Tian; Tianxi Zhang; Jinru Jia; Shengli Yang
The present study describes the gene cloning, overexpression and characterization of a novel nitrilase from hyperthermophilic bacterium Thermotoga maritima MSB8. The nitrilase gene consisted of 804 base pairs, encoding a protein of 268 amino acid residues with a molecular mass of 30.07 kDa after SDS-PAGE analysis. The optimal temperature and pH of the purified enzyme were 45°C and 7.5, respectively. The enzyme demonstrated good temperature tolerance, with 40% residual activity after 60 min of heat treatment at 75°C. The kinetic constants Vmax and Km of this nitrilase toward 3-cyanopyridine were 3.12 μmol/min/mg and 7.63 mM, respectively. Furthermore, this novel nitrilase exhibited a broad spectrum toward the hydrolysis of the aliphatic nitriles among the tested substrates, and particularly was specific to aliphatic dinitriles like succinonitrile, which was distinguished from most nitrilases ever reported. The catalytic efficiency kcat/Km was 0.44 /mM/s toward succinonitrile. This distinct characteristic might enable this nitrilase to be a potential candidate for industrial applications for biosynthesis of carboxylic acid.
Journal of Industrial Microbiology & Biotechnology | 2015
Huayou Chen; Tianxi Zhang; Jinru Jia; Ake Vastermark; Rui Tian; Zhong Ni; Zhi Chen; Keping Chen; Shengli Yang
Extremophiles | 2015
Huayou Chen; Rui Tian; Zhong Ni; Qing Zhang; Tianxi Zhang; Zhi Chen; Keping Chen; Shengli Yang
Journal of Molecular Catalysis B-enzymatic | 2016
Huayou Chen; Zhi Chen; Zhong Ni; Rui Tian; Tianxi Zhang; Jinru Jia; Keping Chen; Shengli Yang
Applied Biochemistry and Biotechnology | 2017
Huayou Chen; Bangguo Wu; Tianxi Zhang; Jinru Jia; Jian Lu; Zhi Chen; Zhong Ni; Tianwei Tan
Applied Biochemistry and Biotechnology | 2015
Rui Tian; Huayou Chen; Zhong Ni; Qing Zhang; Zhongge Zhang; Tianxi Zhang; Chunxia Zhang; Shengli Yang
Journal of Molecular Microbiology and Biotechnology | 2015
Oscar P. Kuipers; Muhammad Afzal; Sulman Shafeeq; Irfan Manzoor; Huayou Chen; Tengyun Sun; Zhong Ni; Yilin Le; Rui Tian; Tianxi Zhang; Zhi Chen; Chunxia Zhang; Taylor L. Fischer; Robert J. White; Katherine F.K. Mares; Devin E. Molnau; Justin J. Donato; Sumeth Imsoonthornruksa; Kamthorn Pruksananonda; Rangsun Parnpai; Ruttachuk Rungsiwiwut; Mariena Ketudat-Cairns; Graciela L. Lorca; Iva Čanak; Adrienn Berkics; Nikolett Bajcsi; Monika Kovacs; Ágnes Belák; Renata Teparić; Anna Maráz