Department of Geoscience and Natural Resource Management, University of Copenhagen, 1958, Frederiksberg, Denmark.
Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden.
Sci Rep. 2020 Oct 1;10(1):16369. doi: 10.1038/s41598-020-73266-y.
Lytic polysaccharide monooxygenase (LPMO) and copper binding protein CopC share a similar mononuclear copper site. This site is defined by an N-terminal histidine and a second internal histidine side chain in a configuration called the histidine brace. To understand better the determinants of reactivity, the biochemical and structural properties of a well-described cellulose-specific LPMO from Thermoascus aurantiacus (TaAA9A) is compared with that of CopC from Pseudomonas fluorescens (PfCopC) and with the LPMO-like protein Bim1 from Cryptococcus neoformans. PfCopC is not reduced by ascorbate but is a very strong Cu(II) chelator due to residues that interacts with the N-terminus. This first biochemical characterization of Bim1 shows that it is not redox active, but very sensitive to HO, which accelerates the release of Cu ions from the protein. TaAA9A oxidizes ascorbate at a rate similar to free copper but through a mechanism that produce fewer reactive oxygen species. These three biologically relevant examples emphasize the diversity in how the proteinaceous environment control reactivity of Cu with O.
溶细胞多糖单加氧酶（LPMO）和铜结合蛋白 CopC 共享一个类似的单核铜位。该位点由 N 端组氨酸和第二个内部组氨酸侧链以称为组氨酸臂的构型定义。为了更好地理解反应性的决定因素，将来自嗜热子囊菌（Thermoascus aurantiacus）的一种描述良好的纤维素特异性 LPMO（TaAA9A）的生化和结构特性与来自荧光假单胞菌（Pseudomonas fluorescens）的 CopC 和来自新生隐球菌（Cryptococcus neoformans）的 LPMO 样蛋白 Bim1 进行了比较。PfCopC 不能被抗坏血酸还原，但由于与 N 端相互作用的残基，它是一种非常强的 Cu(II)螯合剂。Bim1 的首次生化特性表明，它不是氧化还原活性的，但对 HO 非常敏感，HO 会加速铜离子从蛋白质中的释放。TaAA9A 以与游离铜相似的速率氧化抗坏血酸，但通过一种产生较少活性氧的机制。这三个与生物学相关的例子强调了蛋白质环境如何控制 Cu 与 O 的反应性的多样性。
