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Chengyao X, Yan Q, Chaonan D, Xiaopei C, Yanxin W, Ding L, Xianfeng Y, Jian H, Yan H, Zhongli C, Zhoukun L. Enzymatic properties of an efficient glucan branching enzyme and its potential application in starch modification. Protein Expr Purif 2020; 178:105779. [PMID: 33115653 DOI: 10.1016/j.pep.2020.105779] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 09/02/2020] [Accepted: 10/21/2020] [Indexed: 11/29/2022]
Abstract
Glucan branching enzymes (GBEs, EC 2.4.1.18) catalyze the formation of α-1,6-linked branch in starch, which is important for the starch modification with prospective properties. In this study, the aqGBE gene encoding an efficient glucan branching enzyme was cloned from Aquabacterium sp. strain A7-Y and successfully expressed in Escherichia coli BL21 (DE3). The specific activity of the purified recombinant enzyme rAqGBE was 2850 U/mg with potato starch as the optimal substrate, and the Km and Vmax values of rAqGBE were 1.18 mg/mL and 588.2 μmol/min/mg, respectively. Enzymological characterization showed that rAqGBE exhibits its optimal activity under the condition of 40 °C and pH 7.0, respectively, which is independent of calcium ions. Otherwise, rAqGBE-treated potato starch showed different chain length distribution compared with control, the numbers of short chains (degree of polymerization, DP < 7) and long chains (DP > 25) increased from 4.5% to 9.6% and 6.1%-15.7% after enzymatic treatment, respectively. In starch anti-ageing assay, with minimum usage of 0.8 mg rAqGBE per g starch, the rAqGBE-treated potato starch exhibited reduced retrogradation properties. Our results indicate that the branching enzyme AqGBE may therefore be a promising tool for the enzymatic modification of starch.
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Affiliation(s)
- Xia Chengyao
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Qiao Yan
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Dong Chaonan
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Chen Xiaopei
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Wang Yanxin
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Li Ding
- Institute of Veterinary Immunology &Engineering, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, PR China
| | - Ye Xianfeng
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Han Jian
- College of Agriculture, Xinjiang Agricultural University, XinJiang, 830052, China
| | - Huang Yan
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Cui Zhongli
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Li Zhoukun
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Science, Nanjing Agricultural University, Nanjing, 210095, PR China.
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Zhiyong Y, Chaonan D, Ruiying Q, Lijin X, Aihua Z. Photocatalytic degradation of methyl orange by PbXO4 (X=Mo, W). J Colloid Interface Sci 2014; 438:323-331. [PMID: 25454457 DOI: 10.1016/j.jcis.2014.09.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 09/05/2014] [Accepted: 09/14/2014] [Indexed: 10/24/2022]
Abstract
PbMoO4 and PbWO4 are prepared by the simple precipitation method in this work, they show the photocatalytic activities for the degradation of methyl orange in water under the UV light illumination. In the above photocatalytic degradation processes, methyl orange concentration decreases quickly, the total organic carbon (TOC) decreases slowly; inorganic ions (SO4(2-), NO3(-), NO2(-), NH4(+)) can be formed and measured by the ion chromatograph; the pH value in the systems decreases gradually; a small quantity of HO˙(-)·can be generated and measured by the terephthalic acid (TA) indirectly. In order to estimate the roles of active species during the above photocatalytic degradation processes, isopropanol, (NH4)2C2O4, and 1,4-benzoquinone as the scavengers for HO˙, h(+), O2˙(-) are introduced into the systems, respectively. Isopropanol and (NH4)2C2O4 are effective scavengers for active species HO˙ and h(+) respectively, but 1,4-benzoquinone is not a satisfactory scavenger in all cases to capture O2˙(-), at least in this work. At last, PbMoO4 and PbWO4 are characterized by nitrogen sorption, DRS, SEM, TEM and XRD.
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Affiliation(s)
- Yu Zhiyong
- Department of Chemistry, Renmin University of China, Beijing 100872, China.
| | - Dong Chaonan
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Qiu Ruiying
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Xu Lijin
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Zheng Aihua
- Analysis and Testing Center, Beijing Normal University, Beijing 100875, China
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