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| 1 | Overexpression and characterization of a thermostable β-agarase producing neoagarotetraose from a marine isolate Microbulbifer sp.AG1显示文摘An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was expressed and purified from Escherichia coli BL21(DE3). When agarose was used as a substrate, the optimal temperature and pH for the enzyme were 60℃ and 7.5, respectively. The recombinant agarase showed excellent thermostability with 67% and 19% of residual activities after incubation at 50℃ and 60℃ for 1 h, respectively.Except SDS, the recombinant agarase had a relatively good resistance against the detected inhibitors, detergents and urea denaturant. Thin layer chromatography analysis and enzyme assay using p-nitrophenyl-α/β-Dgalactopyranoside revealed that the recombinant agarase was a β-agarase that degraded agarose into neoagarotetraose as the main end product. The enzymatic hydrolysis products with different degree of polymerization exhibited the antioxidant activities. | Yanbing Zhu He Gao Hebin Li Hui Ni Zedong Jiang Lijun Li Anfeng Xiao | 2019 | Acta Oceanologica Sinica2019，38，2： | 1 |
| 2 | Visual detection model of gauge between high signals and contact net显示文摘 | Yu Yong Zhu Xilin Xue Changsong Hui Anfeng | 2011 | Advanced Materials Research2011，，305： | 1 |
| 3 | Purification and biochemical characterization of manganesecontaining superoxide dismutase from deep-sea thermophile Geobacillus sp. EPT3显示文摘Thermostable SOD is a promising enzyme in biotechnological applications. In the present study, thermophile Geobacillus sp. EPT3 was isolated from a deep-sea hydrothermal field in the East Pacific. A thermostable superoxide dismutase(SOD) from this strain was purified to homogeneity by steps of fractional ammonium sulfate precipitation, DEAE-Sepharose chromatography, and Phenyl-Sepharose chromatography. SOD was purified 13.4 fold to homogeneity with a specific activity of 3 354 U/mg and 11.1% recovery. SOD from Geobacillus sp. EPT3 was of the Mn-SOD type, judged by the insensitivity of the enzyme to both KCN and H2O2. SOD was determined to be a homodimer with monomeric molecular mass of 26.0 k Da. It had high thermostability at 50°C and 60°C. At tested conditions, SOD was relatively stable in the presence of some inhibitors and denaturants, such as β-mercaptoethanol(β-ME), dithiothreitol(DTT), phenylmethylsulfonyl fluoride(PMSF), urea, and guanidine hydrochloride. Geobacillus sp. EPT3 SOD showed striking stability across a wide p H range from 5.0 to 11.0. It could withstand denaturants of extremely acidic and alkaline conditions, which makes it useful in the industrial applications. | ZHU Yanbing LI Hebin NI Hui LIU Jingwen XIAO Anfeng CAI Huinong | 2014 | Acta Oceanologica Sinica2014，33，12： | 0 |
| 4 | Substitution of His260 residue alters the thermostability of Pseudoalteromonas carrageenovora arylsulfatase显示文摘This study aimed to improve the thermostability of arylsulfatase from Pseudoalteromonas carrageenovora. A library of P. carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using error-prone PCR. After screening, two mutants of H260L and D84A/H260L showed enhanced thermal stability than the wild-type predecessor (WT). Site-directed mutagenesis demonstrated that only amino acid residue at Position 260 plays an important role in the thermostability of P. carrageenovora arylsulfatase. Thermal inactivation analysis showed that the half-life (t1/2) values at 55°C for H260L, H260I, H260Q, H260F and H260R were 40.6, 48.4, 30.9, 29.1 and 34.5 min, respectively, while that of WT was 9.1 min. Structure modeling demonstrated that the additional hydrogen bonds and/or optimization of surface charge-charge interactions could be responsible for the increased thermostability imparted by H260L, H260I, H260Q, H260F and H260R. | Yanbing Zhu Xiaoqian Yin Han Liu Hebin Li Yanhong Chen Lijun Li Anfeng Xiao Hui Ni | 2019 | Acta Oceanologica Sinica2019，38，6： | 0 |
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