Oxygen Activation at the Active Site of a Fungal Lytic Polysaccharide Monooxygenase.
Oxygen Activation at the Active Site of a Fungal Lytic Polysaccharide Monooxygenase.
复制标题
DOI：
10.1002/anie.201610502
复制
发表时间：
2017-01-16
期刊：
影响因子：
--
通讯作者：
Meilleur F
中科院分区：
文献类型：
--
作者：
O'Dell WB;Agarwal PK;Meilleur F
溶解性多糖单加氧酶由于其通过氧化而不是水解来破坏糖苷键以及增强包括几丁质和纤维素在内的难消化底物的酶促消化的能力而引起了广泛的关注。我们已经确定了高分辨率的X-射线晶体结构的酶从粗糙脉孢菌在静息状态和铜（II）-二氧代中间复合物在没有底物的情况下形成。X射线晶体结构也显示了“预绑定”的分子氧邻近的活性位点。通过中子晶体学和密度泛函理论计算对质子化状态的检查确定了保守的组氨酸在促进氧活化中的作用。这些结果提供了一个新的结构描述无底物的溶解性多糖单加氧酶的氧活化，并提供了见解，可以扩展到酶-底物复合物的反应性。X射线晶体学产生了LPMO酶的第一个结构，其具有结合在组氨酸支架平面中的活化的二氧物种。一个“预绑定”网站的分子氧也确定和中子蛋白质晶体学和DFT计算的特点。
Lytic polysaccharide monooxygenases have attracted vast attention due to their abilities to disrupt glycosidic bonds via oxidation instead of hydrolysis and to enhance enzymatic digestion of recalcitrant substrates including chitin and cellulose. We have determined high resolution X-ray crystal structures of an enzyme from Neurospora crassa in the resting state and of a copper(II)–dioxo intermediate complex formed in the absence of substrate. X-ray crystal structures also revealed “pre-bound” molecular oxygen adjacent to the active site. An examination of protonation states enabled by neutron crystallography and density functional theory calculations identified a role for a conserved histidine in promoting oxygen activation. These results provide a new structural description of oxygen activation by substrate free lytic polysaccharide monooxygenases and provide insights that can be extended to reactivity in the enzyme–substrate complex. X-ray crystallography produces the first structure of an LPMO enzyme with an activated dioxo species bound in the plane of the histidine brace. A “pre-binding” site for molecular oxygen is also identified and characterized with neutron protein crystallography and DFT calculations.