Learning from Nature hwo Two-metal Centres Operate: Studies of Purple Acid Phosphatases (PAP) and Polyphenol Oxidases (PPO)-Enzymes and Models

本项目的主要目的是通过结合酶和模型复合物的结构和功能研究，解决两类双金属酶：紫色酸性磷酸酶（PAP）和多酚氧化酶（PPO与儿茶酚氧化酶（CO）和酪氨酸酶（Tyr））的两种金属离子的各自作用问题。作为起点，我们将进一步推进对结构已知系统（植物PAP和CO）的理解。在分子水平上对其作用机制的描述仍存在一些争议，有几个方面有待阐明。关于活性物质、底物的结合模式（每个金属中心的各自作用）以及H+及其在催化过程中的转移的重要性和作用（pH依赖性）的大量数据缺失。此外，我们将把注意力集中在同一家族的高度重要的酶上，这些酶迄今为止仍未被充分表征：人类PAP和Tyr。我们将根据我们小组的专业知识，纯化并尝试获得这些酶的x射线结构，以评估与已知亲本酶结构的差异，并通过整体比较获得信息。了解酶机制的分子方面是目前生物无机化学中最具挑战性的目标之一，使用跨学科的协同方法似乎是实现这一目标的最有希望的方法。本项目以这种方法为基础，将包括：1。酶的分离和纯化（高量的众所周知的程序-植物PAP和CO-和最终的纯化程序-人类PAP和Tyr）结构（x射线）和生化研究（抑制剂，动力学）仿生模型获得可靠的结构、光谱和反应性特征研究金属中心（模型和酶）的分子、电子和磁性结构的物理方法

The main objective of this project is to address the question of the respective roles of the two metal ions of two classes of bimetallic enzymes: the purple acid phosphatases (PAP) and the polyphenol oxidases (PPO with catechol oxidases (CO) and tyrosinase (Tyr)) via combination of structural and functional studies on enzymes and on model complexes. As a starting point, we will further advance the understanding of structurally-known systems (plant PAP and CO). Some controversies persist in the description of the mechanism of action at the molecular level and several aspects remain to be elucidated. A great deal of data are missing on the active species, the binding mode of the substrate (respective role of each metallic centre) and the importance and role of H+ and their transfer in the catalytic processes (pH dependence). In addition, we will focus our attention on highly important enzymes of the same family which to date remain poorly characterized: human PAP and Tyr. Based on our groups expertises, we will purify and attempt to obtain X-ray structures of these enzymes to assess the differences with the known structures of parent enzymes and get information through an overall comparison. Understanding molecular aspects of enzyme mechanisms is currently among the most challenging objectives in bioinorganic chemistry and using a synergistic interdisciplinary approach appears to be the most promising way of reaching this goal. The present project is built on such an approach and will include: 1. Isolation and purification of enzymes (High amount for well-known procedure - plant PAP and CO- and finalization of purification procedure - human PAP and Tyr) 2. Structural (X-ray) and biochemical studies (inhibitors, kinetics) 3. Biomimetic models to get reliable structural, spectroscopic and reactivity characteristics 4. Physical methods to investigate the molecular, electronic and magnetic structures of metal centres (models and enzymes)