Abstract
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; 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5110-5122 |
| Number of pages | 13 |
| Journal | Journal of the American Chemical Society |
| Volume | 138 |
| Issue number | 15 |
| DOIs | |
| State | Published - May 4 2016 |
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All Science Journal Classification (ASJC) codes
- Catalysis
- Chemistry(all)
- Biochemistry
- Colloid and Surface Chemistry
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Electronic Structure of the Ferryl Intermediate in the α-Ketoglutarate Dependent Non-Heme Iron Halogenase SyrB2 : Contributions to H Atom Abstraction Reactivity. / Srnec, Martin; Wong, Shaun D.; Matthews, Megan L.; Krebs, Carsten; Bollinger, Jr., Joseph M.; Solomon, Edward I.
In: Journal of the American Chemical Society, Vol. 138, No. 15, 04.05.2016, p. 5110-5122.Research output: Contribution to journal › Article
TY - JOUR
T1 - Electronic Structure of the Ferryl Intermediate in the α-Ketoglutarate Dependent Non-Heme Iron Halogenase SyrB2
T2 - Contributions to H Atom Abstraction Reactivity
AU - Srnec, Martin
AU - Wong, Shaun D.
AU - Matthews, Megan L.
AU - Krebs, Carsten
AU - Bollinger, Jr., Joseph M.
AU - Solomon, Edward I.
PY - 2016/5/4
Y1 - 2016/5/4
N2 - 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; 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.
AB - 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; 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.
UR - http://www.scopus.com/inward/record.url?scp=84966417260&partnerID=8YFLogxK
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U2 - 10.1021/jacs.6b01151
DO - 10.1021/jacs.6b01151
M3 - Article
C2 - 27021969
AN - SCOPUS:84966417260
VL - 138
SP - 5110
EP - 5122
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 15
ER -