Department of Biophysics, School of Physical Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, PR China.
Department of Biophysics, School of Physical Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin 300071, PR China; Qilu Institute of Technology, Shandong 250200, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Feb 5;266:120446. doi: 10.1016/j.saa.2021.120446. Epub 2021 Sep 28.
Xanthine oxidase (XO) is a purine catabolic enzyme related to hyperuricemia and gout. Porphyra polysaccharide (PP) is a kind of sulfated polysaccharide with potent biological activity. Herein, the interaction mechanism between PP and XO was studied by enzyme kinetics and multi-spectroscopy methods for the first time. Inhibition kinetics assay showed that PP reversibly inhibited XO activity in a mixed competitive manner with an IC of 10.53 ± 0.69 mg/ml. Fluorescence titration studies and thermodynamic parameter calculations revealed that PP could spontaneously bind to XO through hydrophobic interactions, with a class of binding site. Circular dichroism analysis demonstrated that PP induced secondary structure rearrangement and conformational change of XO. Molecular docking further revealed that PP inserted into the hydrophobic cavity of XO, occupying the catalytic center, leading to the inhibition of XO activity. This study may provide new insights into the inhibitory mechanism of PP as a promising XO inhibitor.
黄嘌呤氧化酶（XO）是一种与高尿酸血症和痛风有关的嘌呤分解酶。紫菜多糖（PP）是一种具有强大生物活性的硫酸多糖。本文首次采用酶动力学和多光谱法研究了 PP 与 XO 的相互作用机制。抑制动力学研究表明，PP 以混合竞争方式可逆地抑制 XO 活性，IC 为 10.53±0.69mg/ml。荧光滴定和热力学参数计算表明，PP 可通过疏水相互作用自发与 XO 结合，存在一类结合位点。圆二色谱分析表明，PP 诱导 XO 的二级结构重排和构象变化。分子对接进一步表明，PP 插入 XO 的疏水腔，占据催化中心，从而抑制 XO 活性。该研究可能为 PP 作为一种有前途的 XO 抑制剂的抑制机制提供新的见解。
