Revisiting the role of electron donors in lytic polysaccharide monooxygenase biochemistry.
Revisiting the role of electron donors in lytic polysaccharide monooxygenase biochemistry.
复制标题
DOI：
10.1042/ebc20220164
复制
发表时间：
2023-04-18
影响因子：
6.4
通讯作者：
中科院分区：
文献类型：
--
作者：
植物细胞壁富含碳水化合物，许多真菌和细菌已经进化到可以利用这种碳源。这些碳水化合物大部分被锁在多糖中，因此这些生物部署了一系列酶，可以从这些具有挑战性的底物中释放单个糖。糖苷水解酶（GHs）是主要负责糖释放的酶；然而，12年前，一种被称为多糖单加氧酶（LPMOs）的酶家族也被证明在这一过程中起着关键作用。LPMOs是铜依赖的氧化酶，可以在多糖链中引入链断裂。最初的研究表明，它们可以通过一个很可能需要将多个电子传递给酶的反应激活O2来攻击底物。最近，有研究表明，如果将H2O2作为辅底物提供给酶而不是O2， LPMO动力学将得到显著改善。激活LPMO和H2O2共底物只需要一个电子，并且该酶已被证明在铜的初始单电子还原后催化多次翻转，如果使用O2则不可能。这导致了对电子供体在LPMO生物化学中的作用的进一步研究，本文旨在强调这一领域的最新发现，并考虑正在进行的研究如何影响我们对自然界中氧化还原过程之间相互作用的理解。
The plant cell wall is rich in carbohydrates and many fungi and bacteria have evolved to take advantage of this carbon source. These carbohydrates are largely locked away in polysaccharides and so these organisms deploy a range of enzymes that can liberate individual sugars from these challenging substrates. Glycoside hydrolases (GHs) are the enzymes that are largely responsible for bringing about this sugar release; however, 12 years ago, a family of enzymes known as lytic polysaccharide monooxygenases (LPMOs) were also shown to be of key importance in this process. LPMOs are copper-dependent oxidative enzymes that can introduce chain breaks within polysaccharide chains. Initial work demonstrated that they could activate O2 to attack the substrate through a reaction that most likely required multiple electrons to be delivered to the enzyme. More recently, it has emerged that LPMO kinetics are significantly improved if H2O2 is supplied to the enzyme as a cosubstrate instead of O2. Only a single electron is required to activate an LPMO and H2O2 cosubstrate and the enzyme has been shown to catalyse multiple turnovers following the initial one-electron reduction of the copper, which is not possible if O2 is used. This has led to further studies of the roles of the electron donor in LPMO biochemistry, and this review aims to highlight recent findings in this area and consider how ongoing research could impact our understanding of the interplay between redox processes in nature.