Nitrogen Oxide Atom-Transfer Redox Chemistry; Mechanism of NO(g) to Nitrite Conversion Utilizing μ-oxo Heme-Fe
III-O-Cu
II(L) Constructs

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autor(en): Hematian S, Kenkel I, Shubina T, Dürr M, Liu JJ, Siegler MA, Ivanovic-Burmazovic I, Karlin KD
Zeitschrift: Journal of the American Chemical Society
Verlag: American Chemical Society
Jahr der Veröffentlichung: 2015
Band: 137
Heftnummer: 20
Seitenbereich: 6602-6615
ISSN: 1520-5126


Abstract


(Chemical Equation Presented) While nitric oxide (NO, nitrogen monoxide) is a critically important signaling agent, its cellular concentrations must be tightly controlled, generally through its oxidative conversion to nitrite (NO2-) where it is held in reserve to be reconverted as needed. In part, this reaction is mediated by the binuclear heme a3/CuB active site of cytochrome c oxidase. In this report, the oxidation of NO(g) to nitrite is shown to occur efficiently in new synthetic μ-oxo heme-FeIII-O-CuII(L) constructs (L being a tridentate or tetradentate pyridyl/alkylamino ligand), and spectroscopic and kinetic investigations provide detailed mechanistic insights. Two new X-ray structures of μ-oxo complexes have been determined and compared to literature analogs. All μ-oxo complexes react with 2 mol equiv NO(g) to give 1:1 mixtures of discrete [(L)CuII(NO2-)]+ plus ferrous heme-nitrosyl compounds; when the first NO(g) equiv reduces the heme center and itself is oxidized to nitrite, the second equiv of NO(g) traps the ferrous heme thus formed. For one μ-oxo heme-FeIII-O-CuII(L) compound, the reaction with NO(g) reveals an intermediate species ("intermediate"), formally a bis-NO adduct, [(NO)(porphyrinate)FeII-(NO2-)-CuII(L)]+ (λmax = 433 nm), confirmed by cryo-spray ionization mass spectrometry and EPR spectroscopy, along with the observation that cooling a 1:1 mixture of [(L)CuII(NO2-)]+ and heme-FeII(NO) to -125°C leads to association and generation of the key 433 nm UV-vis feature. Kinetic-thermodynamic parameters obtained from low-temperature stopped-flow measurements are in excellent agreement with DFT calculations carried out which describe the sequential addition of NO(g) to the μ-oxo complex.



FAU-Autoren / FAU-Herausgeber

Dürr, Maximilian
Lehrstuhl für Bioanorganische Chemie
Ivanovic-Burmazovic, Ivana Prof. Dr.
Lehrstuhl für Bioanorganische Chemie
Kenkel, Isabell
Lehrstuhl für Bioanorganische Chemie
Shubina, Tatyana Dr.
Computer-Chemie-Centrum


Zitierweisen

APA:
Hematian, S., Kenkel, I., Shubina, T., Dürr, M., Liu, J.J., Siegler, M.A.,... Karlin, K.D. (2015). Nitrogen Oxide Atom-Transfer Redox Chemistry; Mechanism of NO(g) to Nitrite Conversion Utilizing μ-oxo Heme-Fe <sup>III</sup>-O-Cu <sup>II</sup>(L) Constructs. Journal of the American Chemical Society, 137(20), 6602-6615. https://dx.doi.org/10.1021/jacs.5b02174

MLA:
Hematian, Shabnam, et al. "Nitrogen Oxide Atom-Transfer Redox Chemistry; Mechanism of NO(g) to Nitrite Conversion Utilizing μ-oxo Heme-Fe <sup>III</sup>-O-Cu <sup>II</sup>(L) Constructs." Journal of the American Chemical Society 137.20 (2015): 6602-6615.

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