Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
J Am Chem Soc. 2017 Oct 4;139(39):13830-13836. doi: 10.1021/jacs.7b07374. Epub 2017 Sep 20.
Iron(II)- and 2-(oxo)-glutarate-dependent oxygenases catalyze diverse oxidative transformations that are often initiated by abstraction of hydrogen from carbon by iron(IV)-oxo (ferryl) complexes. Control of the relative orientation of the substrate C-H and ferryl Fe-O bonds, primarily by direction of the oxo group into one of two cis-related coordination sites (termed inline and offline), may be generally important for control of the reaction outcome. Neither the ferryl complexes nor their fleeting precursors have been crystallographically characterized, hindering direct experimental validation of the offline hypothesis and elucidation of the means by which the protein might dictate an alternative oxo position. Comparison of high-resolution X-ray crystal structures of the substrate complex, an Fe(II)-peroxysuccinate ferryl precursor, and a vanadium(IV)-oxo mimic of the ferryl intermediate in the l-arginine 3-hydroxylase, VioC, reveals coordinated motions of active site residues that appear to control the intermediate geometries to determine reaction outcome.
铁(II)和 2-(氧代)-戊二酸依赖性加氧酶催化多种氧化转化，这些转化通常是由铁(IV)-氧(过氧)配合物从碳上夺取氢引发的。通过将氧原子定向到两个顺式相关的配位位点之一（称为在线和离线），可以控制底物 C-H 和过氧 Fe-O 键的相对取向，这对于控制反应结果可能很重要。过氧配合物及其短暂的前体都没有通过晶体学进行表征，这阻碍了对离线假设的直接实验验证，并阐明了蛋白质可能决定替代氧位置的方式。通过比较高分辨率 X 射线晶体结构，可以比较底物复合物、Fe(II)-过氧琥珀酸过氧前体以及 l-精氨酸 3-羟化酶中过氧中间体的钒(IV)-氧类似物，揭示了活性位点残基的协调运动，这些运动似乎控制了中间体的几何形状，从而决定了反应结果。
