Hansberg Wilhelm
Departamento de Biología Celular y del Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico.
Antioxidants (Basel). 2022 Nov 2;11(11):2173. doi: 10.3390/antiox11112173.
The review focuses on four issues that are critical for the understanding of monofunctional catalases. How hydrogen peroxide (HO) reaches the active site and outcompetes water molecules to be able to function at a very high rate is one of the issues examined. Part of the answer is a gate valve system that is instrumental to drive out solvent molecules from the final section of the main channel. A second issue relates to how the enzyme deals with an unproductive reactive compound I (Cpd I) intermediate. Peroxidatic two and one electron donors and the transfer of electrons to the active site from NADPH and other compounds are reviewed. The new ascribed catalase reactions are revised, indicating possible measurement pitfalls. A third issue concerns the heme to heme oxidation, why this reaction occurs only in some large-size subunit catalases (LSCs), and the possible role of singlet oxygen in this and other modifications. The formation of a covalent bond between the proximal tyrosine with the vicinal residue is analyzed. The last issue refers to the origin and function of the additional C-terminal domain (TD) of LSCs. The TD has a molecular chaperone activity that is traced to a gene fusion between a Hsp31-type chaperone and a small-size subunit catalase (SSC).
本综述聚焦于对理解单功能过氧化氢酶至关重要的四个问题。过氧化氢（H₂O₂）如何到达活性位点并排挤水分子从而能够以非常高的速率发挥作用是所探讨的问题之一。部分答案是一个闸阀系统，它有助于将溶剂分子从主通道的最后一段排出。第二个问题涉及该酶如何处理非生产性的反应性化合物I（Cpd I）中间体。对过氧化物酶的双电子和单电子供体以及电子从NADPH和其他化合物转移到活性位点的过程进行了综述。对新归因的过氧化氢酶反应进行了修订，指出了可能的测量陷阱。第三个问题涉及血红素到血红素的氧化，为什么这种反应仅在一些大尺寸亚基过氧化氢酶（LSCs）中发生，以及单线态氧在这种及其他修饰中的可能作用。分析了近端酪氨酸与邻近残基之间共价键的形成。最后一个问题涉及LSCs额外的C末端结构域（TD）的起源和功能。TD具有分子伴侣活性，这可追溯到Hsp31型伴侣蛋白与小尺寸亚基过氧化氢酶（SSC）之间的基因融合。
