Astashkin Andrei V, Klein Eric L, Ganyushin Dmitry, Johnson-Winters Kayunta, Neese Frank, Kappler Ulrike, Enemark John H
Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.
Phys Chem Chem Phys. 2009 Aug 21;11(31):6733-42. doi: 10.1039/b907029j. Epub 2009 Jul 13.
The electron spin echo envelope modulation (ESEEM) investigation of the high-pH (hpH) form of sulfite oxidase (SO) and sulfite dehydrogenase (SDH) prepared in buffer enriched with H(2)(17)O reveals the presence of three types of exchangeable oxygen atoms at the molybdenum center. Two of these oxygen atoms belong to the equatorial OH ligand and the axial oxo ligand, and are characterized by (17)O hyperfine interaction (hfi) constants of about 37 MHz and 6 MHz, respectively. The third oxygen has an isotropic hfi constant of 3-4 MHz and likely belongs to a hydroxyl moiety hydrogen-bonded to the equatorial OH ligand. This exchangeable oxygen atom is not observed in the ESEEM spectra of the Y236F mutant of SDH, where the active site tyrosine has been replaced by phenylalanine.
在富含H₂¹⁷O的缓冲液中制备的亚硫酸盐氧化酶（SO）和亚硫酸盐脱氢酶（SDH）的高pH（hpH）形式的电子自旋回波包络调制（ESEEM）研究表明，钼中心存在三种可交换氧原子。其中两个氧原子属于赤道面的OH配体和轴向的氧代配体，其特征在于¹⁷O超精细相互作用（hfi）常数分别约为37 MHz和6 MHz。第三个氧的各向同性hfi常数为3 - 4 MHz，可能属于与赤道面OH配体氢键结合的羟基部分。在SDH的Y236F突变体的ESEEM光谱中未观察到这种可交换氧原子，该突变体的活性位点酪氨酸已被苯丙氨酸取代。
