The Interaction of Chromium(VI) with Urease in Solution |
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| Authors: | Hong-Mei Zhang Gen-Cheng Zhang Yan-Qing Wang |
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| Institution: | 1. Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Yancheng City, Jiangsu Province, 224002, People’s Republic of China
2. Institute of Applied Chemistry and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province, 224002, People’s Republic of China
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| Abstract: | The interaction between K2Cr2O7 and urease was investigated using fluorescence, UV-vis absorption, and circular dichroism (CD) spectroscopy. The experimental results showed that the fluorescence quenching of urease by K2Cr2O7 was a result of the formation of K2Cr2O7–urease complex. The apparent binding constant K A between K2Cr2O7 and urease at 295, 302, and 309 K were obtained to be 2.14?×?104, 1.96?×?104, and 1.92?×?104 L mol?1, respectively. The thermodynamic parameters, ΔH° and ΔS° were estimated to be ?5.90 kJ mol?1, 43.67 J mol?1 K?1 according to the Van’t Hoff equation. The electrostatic interaction played a major role in stabilizing the complex. The distance r between donor (urease) and acceptor (K2Cr2O7) was 5.08 nm. The effect of K2Cr2O7 on the conformation of urease was analyzed using UV-vis absorption, CD, synchronous fluorescence spectroscopy, and three-dimensional fluorescence spectra, the environment around Trp and Tyr residues were altered. |
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