Department of Molecular and Structural Biochemistry, North Carolina State University and Biology and Soft Matter Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville and Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
Angew Chem Int Ed Engl. 2017 Jan 16;56(3):767-770. doi: 10.1002/anie.201610502. Epub 2016 Dec 22.
Lytic polysaccharide monooxygenases have attracted vast attention owing 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.
溶菌多糖单加氧酶因其能够通过氧化而不是水解来打断糖苷键，以及增强对包括几丁质和纤维素在内的难消化基质的酶促消化的能力而受到广泛关注。我们已经确定了粗糙脉孢菌中一种酶在静止状态下和在没有底物的情况下形成的铜（II）双氧中间复合物的高分辨率 X 射线晶体结构。X 射线晶体结构还揭示了活性位点附近“预结合”的分子氧。通过中子晶体学和密度泛函理论计算确定的质子化状态的检查确定了保守组氨酸在促进氧活化中的作用。这些结果提供了无底物溶菌多糖单加氧酶氧活化的新结构描述，并提供了可以扩展到酶-底物复合物中反应性的见解。
