State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Science, Guangxi Normal University, Guilin 541004, P. R. China.
College of Food and Bioengineering, Hezhou University, Hezhou 542899, P. R. China.
ACS Appl Bio Mater. 2021 Sep 20;4(9):6962-6973. doi: 10.1021/acsabm.1c00628. Epub 2021 Aug 18.
The dephosphorylation that involves the removal of a phosphate group from a substrate molecule plays a significant role in living organisms. An enzyme mimic (nanozyme) with phosphatase-like catalytic activity has recently received attention in terms of its capacity for dephosphorylation. In this study, three types of highly porous oxyhydroxide with remarkable triphosphatase-like catalytic activities, ZrOOH, GdOOH, and HfOOH, have been prepared through the transformation of metal-organic frameworks (MOFs) using a simple alkaline hydrolysis method. The triphosphatase mimetic activities of ZrOOH, GdOOH, and HfOOH were then thoroughly investigated and verified. In particular, an isotopic tracing experiment revealed that abundant surface hydroxyls could serve as nucleophilic agents to directly attack the electropositive phosphorus atom, causing the cleavage of the terminal phosphoester bonds of phosphoester substrate molecules. The kinetic analysis provided calculated values of of 105.7, 90.5, and 46.1 μM, while the values were 3.57, 4.76, and 2.74 × 10 M s and values were estimated to be 47.52, 41.15, and 52.79 kJ/mol for ZrOOH, GdOOH, and HfOOH, respectively. The chromium(III) ions acting as "poisoning" inhibitors efficiently downregulated the triphosphatase mimetic activity of GdOOH. On the basis of this effect, a colorimetric chromium(III) ion-sensing system was explored, which provided a relevant linear response range for the detection of chromium(III) ions of 5.0-200 μM and a low detection limit of 0.84 μM. This work not only shows the great potential of ZrOOH, GdOOH, and HfOOH as triphosphatase nanozymes but also deepens our understanding of the role of surface hydroxyls on phosphatase-mimicking nanozyme catalytic dephosphorization, which could be used in the rational design of phosphatase-mimicking nanozymes. Furthermore, the developed colorimetric sensing system could be applied to chromium(III) ion detection in biological systems.
去磷酸化涉及从底物分子上去除磷酸基团，在生物体中起着重要作用。具有类似磷酸酶催化活性的酶模拟物（纳米酶）因其去磷酸化能力而受到关注。在这项研究中，通过使用简单的碱性水解方法将金属有机骨架（MOFs）转化为三种具有显著三磷酸酶样催化活性的高多孔氧氢氧化物，ZrOOH、GdOOH 和 HfOOH。然后彻底研究和验证了 ZrOOH、GdOOH 和 HfOOH 的三磷酸酶模拟活性。特别是，同位素示踪实验表明，丰富的表面羟基可以作为亲核试剂直接攻击正电性的磷原子，导致磷酸酯底物分子的末端磷酸酯键的断裂。动力学分析提供了 105.7、90.5 和 46.1 μM 的 值，而 值分别为 3.57、4.76 和 2.74 × 10 M s 和 值分别估计为 47.52、41.15 和 52.79 kJ/mol 对于 ZrOOH、GdOOH 和 HfOOH。作为“中毒”抑制剂的三价铬离子可以有效下调 GdOOH 的三磷酸酶模拟活性。在此基础上，探索了一种比色铬（III）离子传感系统，为检测铬（III）离子提供了 5.0-200 μM 的相关线性响应范围和 0.84 μM 的低检测限。这项工作不仅展示了 ZrOOH、GdOOH 和 HfOOH 作为三磷酸酶纳米酶的巨大潜力，还加深了我们对表面羟基在磷酸酶模拟纳米酶催化去磷酸化中的作用的理解，这可用于磷酸酶模拟纳米酶的合理设计。此外，开发的比色传感系统可应用于生物系统中铬（III）离子的检测。
