Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States.
Zoologisches Institut─Strukturbiologie, Zentrum für Biochemie und Molekularbiologie, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
Inorg Chem. 2023 Apr 10;62(14):5315-5319. doi: 10.1021/acs.inorgchem.3c00342. Epub 2023 Mar 27.
X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data have been used to characterize the coordination environment for the catalytic Mo site of YcbX in two different oxidation states. In the oxidized state, the Mo(VI) ion is coordinated by two terminal oxo ligands, a thiolate S atom from cysteine, and two S donors from the bidentate pyranopterin ene-1,2-dithiolate (pyranopterin dithiolene). Upon reduction, it is the more basic equatorial oxo ligand that is protonated, with a Mo-O bond distance that is best described as either a short Mo-OH bond or a long Mo-OH bond. Mechanistic implications for substrate reduction are discussed in light of these structural details.
X 射线吸收近边结构（XANES）和扩展 X 射线吸收精细结构（EXAFS）数据已被用于表征 YcbX 催化钼位点在两种不同氧化态下的配位环境。在氧化态下，Mo(VI)离子由两个末端氧配体、一个来自半胱氨酸的硫醇 S 原子和来自双齿吡喃并[4,3-b]并噻唑烯-1,2-二硫醇（吡喃并噻唑二硫醇）的两个 S 供体配位。还原后，更具碱性的赤道氧配体被质子化，Mo-O 键距离最好描述为短 Mo-OH 键或长 Mo-OH 键。根据这些结构细节，讨论了对底物还原的机制影响。
