Electronic Structure of the Ferryl Intermediate in the α-Ketoglutarate Dependent Non-Heme Iron Halogenase SyrB2: Contributions to H Atom Abstraction Reactivity

0458875 - ÚFCH JH 2017 RIV US eng J - Článek v odborném periodiku
Srnec, Martin - Wong, S. D. - Matthews, M. L. - Krebs, C. - Bollinger, J. M. - Solomon, E. I.
Electronic Structure of the Ferryl Intermediate in the α-Ketoglutarate Dependent Non-Heme Iron Halogenase SyrB2: Contributions to H Atom Abstraction Reactivity.
Journal of the American Chemical Society. Roč. 138, č. 15 (2016), s. 5110-5122. ISSN 0002-7863. E-ISSN 1520-5126
Grant CEP: GA ČR(CZ) GJ15-10279Y
Institucionální podpora: RVO:61388955
Klíčová slova: Ferryl intermediate * syringomycin halogenase * electronic structure
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 13.858, rok: 2016

Low temperature magnetic circular dichroism (LT MCD) spectroscopy in combination with quantum-chemical calculations are used to define the electronic structure associated with the geometric structure of the FeIV═O intermediate in SyrB2 that was previously determined by nuclear resonance vibrational spectroscopy. These studies elucidate key frontier molecular orbitals (FMOs) and their contribution to H atom abstraction reactivity. The VT MCD spectra of the enzymatic S = 2 FeIV═O intermediate with Br– ligation contain information-rich features that largely parallel the corresponding spectra of the S = 2 model complex (TMG3tren)FeIV═O (Srnec, M.; Wong, S. D.; England, J.; Que, L. Jr.; Solomon, E. I. Proc. Natl. Acad. Sci. USA 2012, 109, 14326–14331). However, quantitative differences are observed that correlate with π-anisotropy and oxo donor strength that perturb FMOs and affect reactivity. Due to π-anisotropy, the FeIV═O active site exhibits enhanced reactivity in the direction of the substrate cavity that proceeds through a π-channel that is controlled by perpendicular orientation of the substrate C–H bond relative to the halide–FeIV═O plane. Also, the increased intrinsic reactivity of the SyrB2 intermediate relative to the ferryl model complex is correlated to a higher oxyl character of the FeIV═O at the transition states resulting from the weaker ligand field of the halogenase.
Trvalý link: http://hdl.handle.net/11104/0259095