| Effect of Urea on Activity and Conformation of a Glycoprotein |
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| 作者姓名： | 魏香 王晓云 周波 周海梦 |
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| 作者单位： | Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China，College of Life Science Shandong Agricultural University Taian 271018 China，College of Life Science Shandong Agricultural University Taian 271018 China，Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China |
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| 基金项目： | Supported by the National Natural Science Foundation of China (No. 30471261) |
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| 摘 要： | Introduction In some enzymes, inactivation occurs before noticeable conformational change can be detected during denaturation by guanidinium chloride or urea1-6]. Tsou7] suggested that enzyme active sites are formed by relatively weak molecular interact…
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| 关 键 词： | 肌醇六磷酸酶 尿素变性 失活 醣蛋白 |
| 收稿时间： | 2005-10-13 |
| 修稿时间： | 2005-10-132006-03-10 |
Effect of Urea on Activity and Conformation of a Glycoprotein |
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| WEI Xiang,WANG Xiaoyun,ZHOU Bo,ZHOU Haimeng.Effect of Urea on Activity and Conformation of a Glycoprotein[J].Tsinghua Science and Technology,2006,11(4):400-407. |
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| Authors: | WEI Xiang WANG Xiaoyun ZHOU Bo ZHOU Haimeng |
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| Institution: | Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China; College of Life Science, Shandong Agricultural University, Taian 271018, China |
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| Abstract: | The changes of the activity and conformation of Aspergillus niger phytase in urea were detected by far-ultraviolet circular dichroism (CD) spectra, fluorescence spectra, and enzyme activity assays. The results show that no enzyme activity can be detected after phytase is incubated for 10 h in 3.0 mol/L urea, even though at this urea concentration, less than 20% of the tertiary and secondary structures in the native enzyme changed. The inactivation reaction kinetics is found to be a monophasic first-order reaction, but the unfolding is a biphasic process consisting of two first-order reactions. The inactivation rates of the free enzyme and the substrate-enzyme complex are much faster than the conformational changes during urea denaturation. All of the results indicate that, as a glycoprotein, phytase's activity is strongly dependent on its conformational integrity. The phytase active sites seem to be located in a limited region in the molecule and display more conformational fragility and flexibility to denaturants than enzyme molecular structure as a whole. |
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| Keywords: | phytase urea denaturation inactivation unfolding |
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