Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
Acc Chem Res. 2021 Apr 6;54(7):1673-1684. doi: 10.1021/acs.accounts.0c00666. Epub 2021 Feb 18.
The selective cleavage of peptide bonds in proteins is of paramount importance in many areas of the biological and medical sciences, playing a key role in protein structure/function/folding analysis, protein engineering, and targeted proteolytic drug design. Current applications that depend on selective protein hydrolysis largely rely on costly proteases such as trypsin, which are sensitive to the pH, ionic strength, and temperature conditions. Moreover, >95% of peptides deposited in databases are generated from trypsin digests, restricting the information within the analyzed proteomes. On the other hand, harsh and toxic chemical reagents such as BrCN are very active but cause permanent modifications of certain amino acid residues. Consequently, transition-metal complexes have emerged as smooth and selective artificial proteases owing to their ability to provide larger fragments and complementary structural information. In the past decade, our group has discovered the unique protease activity of diverse metal-oxo clusters (MOC) and pioneered a distinctive approach to the development of selective artificial proteases. In contrast to classical coordination complexes which often depend on amino acid side chains to control the regioselectivity, the selectivity profile of MOCs is determined by a complex combination of structural factors, such as the protein surface charge, metal coordination to specific side chains, and hydrogen bonding between the protein surface and the MOC scaffold.In this Account, we present a critical overview of our detailed kinetic, spectroscopic, and crystallographic studies in MOC-assisted peptide bond hydrolysis, from its origins to the current rational and detailed mechanistic understanding. To this end, reactivity trends related to the structure and properties of MOCs based on the hydrolysis of small model peptides and key structural aspects governing the selectivity of protein hydrolysis are presented. Finally, our endeavors in seeking the next generation of heterogeneous MOC-based proteases are briefly discussed by embedding MOCs in metal-organic frameworks or using them as discrete nanoclusters in the development of artificial protease-like materials (i.e., nanozymes). The deep and comprehensive understanding sought experimentally and theoretically over the years in aqueous systems with intrinsic polar and charged substrates provides a unique view of the reactivity between inorganic moieties and biomolecules, thereby broadly impacting several different fields (e.g., catalysis in biochemistry, inorganic chemistry, and organic chemistry).
蛋白质中肽键的选择性切割在生物和医学科学的许多领域都至关重要，在蛋白质结构/功能/折叠分析、蛋白质工程和靶向蛋白水解药物设计中发挥着关键作用。目前依赖于选择性蛋白水解的应用主要依赖于昂贵的蛋白酶，如胰蛋白酶，它们对 pH 值、离子强度和温度条件敏感。此外，数据库中 95%以上的肽都是由胰蛋白酶消化产生的，这限制了分析蛋白质组中的信息。另一方面，苛刻且有毒的化学试剂（如 BrCN）虽然非常活跃，但会导致某些氨基酸残基发生永久性修饰。因此，过渡金属配合物因其能够提供更大的片段和互补的结构信息而成为了具有选择性的人工蛋白酶。在过去的十年中，我们小组发现了不同的金属氧簇（MOC）的独特蛋白酶活性，并开创了一种独特的方法来开发具有选择性的人工蛋白酶。与通常依赖于氨基酸侧链来控制区域选择性的经典配位配合物不同，MOC 的选择性轮廓由结构因素的复杂组合决定，例如蛋白质表面电荷、金属与特定侧链的配位以及蛋白质表面与 MOC 支架之间的氢键。在本报告中，我们对我们在 MOC 辅助肽键水解方面的详细动力学、光谱和晶体学研究进行了批判性概述，从其起源到目前对合理和详细的机制理解。为此，介绍了基于小模型肽水解的 MOC 结构和性质与反应性之间的趋势以及控制蛋白质水解选择性的关键结构方面。最后，通过将 MOC 嵌入金属有机骨架或将其用作人工蛋白酶样材料（即纳米酶）中离散纳米簇，简要讨论了我们在寻找下一代基于多相 MOC 的蛋白酶方面的努力。多年来在具有固有极性和带电底物的水相系统中进行的实验和理论上的深入和全面理解为无机部分与生物分子之间的反应性提供了独特的视角，从而广泛影响了几个不同的领域（例如，生物化学、无机化学和有机化学中的催化）。
