Nature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from the two abundant resources sunlight and water. The thermodynamically demanding photosynthetic water splitting is catalyzed by the oxygen-evolving complex in photosystem II (OEC-PSII), which comprises a distorted tetramanganese–calcium cluster (CaMn₄O₅) as catalytic core. As an ubiquitous concept for fine-tuning and regulating the reactivity of the active site of metalloenzymes, the surrounding protein domain creates a sophisticated environment that promotes substrate preorganization through secondary, noncovalent interactions such as hydrogen bonding or electrostatic interactions. Based on the high-resolution X-ray structure of PSII, several water channels were identified near the active site, which are filled with extensive hydrogen-bonding networks of preorganized water molecules, connecting the OEC with the protein surface. As an integral part of the outer coordination sphere of natural metalloenzymes, these channels control the substrate and product delivery, carefully regulate the proton flow by promoting pivotal proton-coupled electron transfer processes, and simultaneously stabilize short-lived oxidized intermediates, thus highlighting the importance of an ordered water network for the remarkable efficiency of the natural OEC.

中文翻译：

---

受限空间中的仿生水预组织，用于金属超分子钌结构中的高效水氧化催化

大自然通过发明最复杂的生物过程之一，即自然光合作用，建立了一种可持续的方式来维持地球上的有氧生命，它为我们提供了来自阳光和水这两种丰富资源的有机物和分子氧。热力学要求高的光合水分解是由光系统 II (OEC-PSII) 中的释氧复合物催化的，该复合物包含一个扭曲的四锰钙簇 (CaMn ₄ O ₅ ) 作为催化核心。作为微调和调节金属酶活性位点反应性的普遍概念，周围的蛋白质结构域创建了一个复杂的环境，通过氢键或静电相互作用等次级非共价相互作用促进底物预组织。基于PSII的高分辨率X射线结构，在活性位点附近发现了多个水通道，这些水通道充满了预组织水分子的广泛氢键网络，将OEC与蛋白质表面连接起来。作为天然金属酶外配位层的组成部分，这些通道控制底物和产物的传递，通过促进关键的质子耦合电子转移过程来仔细调节质子流，并同时稳定短寿命的氧化中间体，从而凸显了重要性有序的水网络​​，以实现自然 OEC 的卓越效率。