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Ma L, Liu Z, Kong Z, Wang M, Li T, Zhu H, Wan Q, Liu D, Shen Q. Functional characterization of a novel copper-dependent lytic polysaccharide monooxygenase TgAA11 from Trichoderma guizhouense NJAU 4742 in the oxidative degradation of chitin. Carbohydr Polym 2021; 258:117708. [DOI: 10.1016/j.carbpol.2021.117708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/14/2020] [Accepted: 01/22/2021] [Indexed: 01/05/2023]
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Chen YY, Li MS, Yun X, Xia F, Hu MJ, Jin T, Cao MJ, Lai D, Chen G, Liu GM. Site-Directed Mutations of Calcium-Binding Sites Contribute to Reducing the Immunoreactivity of the EF-Hand Sarcoplasmic Calcium-Binding Protein in Scylla paramamosain. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:428-436. [PMID: 33377774 DOI: 10.1021/acs.jafc.0c05733] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In order to reduce the immunoreactivity of sarcoplasmic calcium-binding protein (SCP), site-directed mutations were used to replace key amino acids in the conformational epitopes and calcium-binding sites. The mutant SCPs (mSCPs) were expressed in Escherichia coli, and their immunoreactivities were analyzed using iELISA and basophil activation assays. Furthermore, the structural changes of mSCPs were determined from the circular dichroism spectra. The iELISA results showed that mSCPs could effectively inhibit the binding of wild-type SCP (wtSCP) to sensitive serum, with inhibition rates that reached 90%. Moreover, mSCPs could downregulate the expression levels of CD63 and CD203c on the basophil surface. Compared with wtSCP, the peak values were significantly changed, and the calcium binding ability was impaired, which explained the decline in immunoreactivities of the mSCPs. All of the data confirmed that this approach was effective in reducing the immunoreactivity of SCP and could be applied to other shellfish allergens.
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Affiliation(s)
- Yi-Yu Chen
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Jimei University, Xiamen, Fujian 361021, China
| | - Meng-Si Li
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Jimei University, Xiamen, Fujian 361021, China
| | - Xiao Yun
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Jimei University, Xiamen, Fujian 361021, China
| | - Fei Xia
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Jimei University, Xiamen, Fujian 361021, China
| | - Meng-Jun Hu
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Jimei University, Xiamen, Fujian 361021, China
| | - Tengchuan Jin
- Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, University of Science & Technology of China, Hefei, Anhui 230026, China
| | - Min-Jie Cao
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Jimei University, Xiamen, Fujian 361021, China
| | - Dong Lai
- The Second Affiliated Hospital of Xiamen Medical College, Xiamen, Fujian 361021, China
| | - Guixia Chen
- Women and Children's Hospital Affiliated to Xiamen University, Xiamen, Fujian 361003, China
| | - Guang-Ming Liu
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Jimei University, Xiamen, Fujian 361021, China
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Structural and functional insights into thermostable and organic solvent stable variant Pro247-Ser of Bacillus lipase. Int J Biol Macromol 2017; 108:845-852. [PMID: 29101046 DOI: 10.1016/j.ijbiomac.2017.10.176] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 10/14/2017] [Accepted: 10/30/2017] [Indexed: 12/18/2022]
Abstract
Thermostability of enzymes is an important issue in protein engineering and has been studied in detail. Still there is no hard and fast rule to define the conditions which will provide thermal stability. Understanding the various factors and mechanism responsible for thermal stability will add on new insights into our present knowledge in this area. Pro247-Ser variant was constructed based on homology modelling and rational design. It exhibited 60 fold increase in thermal stability at 60°C and+0.7M shift in C1/2 value for urea denaturation as compared to WT. Variant displayed noticeable tolerance to organic solvents. With decrease in Km, catalytic efficiency of Pro247-Ser variant was increased by 12 fold. The activity and stability assay including circular dichroism and fluorescence spectroscopy favoured increased thermal performance of variant. Hydrolytic activity of variant was found to be high in comparison to control for all p-nitrophenol esters investigated. The immobilized variant enzyme demonstrated nearly two fold enhanced conversion of methyl oleate than WT enzyme. The additional molecular interactions of variant residue might contribute to increased thermostability of lipase. The homology modeling predicted formation of additional hydrogen bonds between Ser247/O-Thr251/OG1 as well as Ser247/O-Glu250/N.
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