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Your search keyword '"Ding, Junmei"' showing total 22 results
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22 results on '"Ding, Junmei"'

4. Distinctive molecular and biochemical characteristics of a glycoside hydrolase family 20 β-N-acetylglucosaminidase and salt tolerance

Author

Zunxi Huang, Zhou Junpei, Bo Xu, Rui Liu, Ding Junmei, Qian Wu, Zhifeng Song, Nanyu Han, Rui Zhang, Junjun Li, and Tang Xianghua

Subjects
0301 basic medicine, Glycoside Hydrolases, Protein Conformation, lcsh:Biotechnology, Microbacterium, Lysine, Chitobiose, Acetylglucosamine, Substrate Specificity, Microbiology, 03 medical and health sciences, chemistry.chemical_compound, Chitin, lcsh:TP248.13-248.65, Acetylglucosaminidase, Enzyme Stability, Aspartic acid, Glycoside hydrolase, chemistry.chemical_classification, Binding Sites, biology, Salt Tolerance, biology.organism_classification, Enzyme assay, Activity, Actinobacteria, Enzyme Activation, N-Acetylglucosaminide tolerance, 030104 developmental biology, Enzyme, Biochemistry, chemistry, biology.protein, Salts, β-N-Acetylglucosaminidase, Protein Binding, Research Article, Biotechnology
Abstract

Background Enzymatic degradation of chitin has attracted substantial attention because chitin is an abundant renewable natural resource, second only to lignocellulose, and because of the promising applications of N-acetylglucosamine in the bioethanol, food and pharmaceutical industries. However, the low activity and poor tolerance to salts and N-acetylglucosamine of most reported β-N-acetylglucosaminidases limit their applications. Mining for novel enzymes from new microorganisms is one way to address this problem. Results A glycoside hydrolase family 20 (GH 20) β-N-acetylglucosaminidase (GlcNAcase) was identified from Microbacterium sp. HJ5 harboured in the saline soil of an abandoned salt mine and was expressed in Escherichia coli. The purified recombinant enzyme showed specific activities of 1773.1 ± 1.1 and 481.4 ± 2.3 μmol min−1 mg−1 towards p-nitrophenyl β-N-acetylglucosaminide and N,N'-diacetyl chitobiose, respectively, a V max of 3097 ± 124 μmol min−1 mg−1 towards p-nitrophenyl β-N-acetylglucosaminide and a K i of 14.59 mM for N-acetylglucosamine inhibition. Most metal ions and chemical reagents at final concentrations of 1.0 and 10.0 mM or 0.5 and 1.0% (v/v) had little or no effect (retaining 84.5 − 131.5% activity) on the enzyme activity. The enzyme can retain more than 53.6% activity and good stability in 3.0–20.0% (w/v) NaCl. Compared with most GlcNAcases, the activity of the enzyme is considerably higher and the tolerance to salts and N-acetylglucosamine is much better. Furthermore, the enzyme had higher proportions of aspartic acid, glutamic acid, alanine, glycine, random coils and negatively charged surfaces but lower proportions of cysteine, lysine, α-helices and positively charged surfaces than its homologs. These molecular characteristics were hypothesised as potential factors in the adaptation for salt tolerance and high activity of the GH 20 GlcNAcase. Conclusions Biochemical characterization revealed that the GlcNAcase had novel salt–GlcNAc tolerance and high activity. These characteristics suggest that the enzyme has versatile potential in biotechnological applications, such as bioconversion of chitin waste and the processing of marine materials and saline foods. Molecular characterization provided an understanding of the molecular–function relationships for the salt tolerance and high activity of the GH 20 GlcNAcase. Electronic supplementary material The online version of this article (doi:10.1186/s12896-017-0358-1) contains supplementary material, which is available to authorized users.

Published
2017

5. Partial DNA-guided Cas9 enables genome editing with reduced off-target activity

Author

Yin, Hao, primary, Song, Chun-Qing, additional, Suresh, Sneha, additional, Kwan, Suet-Yan, additional, Wu, Qiongqiong, additional, Walsh, Stephen, additional, Ding, Junmei, additional, Bogorad, Roman L, additional, Zhu, Lihua Julie, additional, Wolfe, Scot A, additional, Koteliansky, Victor, additional, Xue, Wen, additional, Langer, Robert, additional, and Anderson, Daniel G, additional

Published
2018
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6. Structure-guided chemical modification of guide RNA enables potent non-viral in vivo genome editing

Author

Yin, Hao, primary, Song, Chun-Qing, additional, Suresh, Sneha, additional, Wu, Qiongqiong, additional, Walsh, Stephen, additional, Rhym, Luke Hyunsik, additional, Mintzer, Esther, additional, Bolukbasi, Mehmet Fatih, additional, Zhu, Lihua Julie, additional, Kauffman, Kevin, additional, Mou, Haiwei, additional, Oberholzer, Alicia, additional, Ding, Junmei, additional, Kwan, Suet-Yan, additional, Bogorad, Roman L, additional, Zatsepin, Timofei, additional, Koteliansky, Victor, additional, Wolfe, Scot A, additional, Xue, Wen, additional, Langer, Robert, additional, and Anderson, Daniel G, additional

Published
2017
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7. Characterization of a novel low-temperature-active, alkaline and sucrose-tolerant invertase

Author

Han Nanyu, Tang Xianghua, Yajie Gao, He Limei, Huang Zunxi, Xu Bo, Ding Junmei, Qian Wu, Rui Zhang, Junpei Zhou, and Junjun Li

Subjects
0106 biological sciences, 0301 basic medicine, Sucrose, Glycosylation, Protein Conformation, Glycine, Bacillus, 01 natural sciences, Article, Substrate Specificity, 03 medical and health sciences, chemistry.chemical_compound, Hydrolysis, Sequence Analysis, Protein, Catalytic Domain, Escherichia coli, Glycoside hydrolase, Enzyme kinetics, Proline, chemistry.chemical_classification, Multidisciplinary, beta-Fructofuranosidase, Temperature, Hydrogen-Ion Concentration, Recombinant Proteins, Kinetics, 030104 developmental biology, Enzyme, Invertase, chemistry, Biochemistry, Thermodynamics, 010606 plant biology & botany
Abstract

A glycoside hydrolase family 32 invertase from Bacillus sp. HJ14 was expressed in Escherichia coli. The purified recombinant enzyme (rInvHJ14) showed typical biochemical properties of low-temperature-active and alkaline enzymes: (i) rInvHJ14 was active and stable in the range of pH 7.0–9.5 with an apparent pH optimum of 8.0; (ii) rInvHJ14 was most active but not stable at 30–32.5 °C, with 19.7, 48.2 and 82.1% of its maximum activity when assayed at 0, 10 and 20 °C, respectively and the Ea, ΔG* (30 °C), Km (30 °C) and kcat (30 °C) values for hydrolysis of sucrose by rInvHJ14 was 47.6 kJ mol−1, 57.6 kJ mol−1, 62.9 mM and 746.2 s−1, respectively. The enzyme also showed strong sucrose tolerance. rInvHJ14 preserved approximately 50% of its highest activity in the presence of 2045.0 mM sucrose. Furthermore, potential factors for low-temperature-active and alkaline adaptations of rInvHJ14 were presumed. Compared with more thermostable homologs, rInvHJ14 has a higher frequency of glycine residues and a longer loop but a lower frequency of proline residues (especially in a loop) in the catalytic domain. The catalytic pockets of acid invertases were almost negatively charged while that of alkaline rInvHJ14 was mostly positively charged.

Published
2016

16. Metagenomic analysis of the Rhinopithecus bieti fecal microbiome reveals a broad diversity of bacterial and glycoside hydrolase profiles related to lignocellulose degradation

Author

Xu, Bo, primary, Xu, Weijiang, additional, Li, Junjun, additional, Dai, Liming, additional, Xiong, Caiyun, additional, Tang, Xianghua, additional, Yang, Yunjuan, additional, Mu, Yuelin, additional, Zhou, Junpei, additional, Ding, Junmei, additional, Wu, Qian, additional, and Huang, Zunxi, additional

Published
2015
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