Details

Autor(en) / Beteiligte

• Li, Cai-Qin
• Yang, Hua-Qing
• Xu, Jian
• Hu, Chang-Wei

Titel

Hydroxylation mechanism of methane and its derivatives over designed methane monooxygenase model with peroxo dizinc coreElectronic supplementary information (ESI) available: Zero-point energies (ZPE) (hartree), total energies (Ec) (hartree) corrected by ZPE, and relative energies (Er) (kJ mol−1) of various species with respect to reactants at the B3LYP/6-311++G(d, p), Lanl2dz level in protein solution environment. The standard orientations and vibrational frequencies of various species at the B3

Erscheinungsjahr

2012-04

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The peroxo dizinc Zn 2 O 2 complex Q coordinated by imidazole and carboxylate groups for each Zn center has been designed to model the hydroxylase component of methane monooxygenase (MMO) enzyme, on the basis of the experimentally available structure information of enzyme with divalent zinc ion and the MMO with Fe 2 O 2 core. The reaction mechanism for the hydroxylation of methane and its derivatives catalyzed by Q has been investigated at the B3LYP*/cc-pVTZ, Lanl2tz level in protein solution environment. These hydroxylation reactions proceed via a radical-rebound mechanism, with the rate-determining step of the C-H bond cleavage. This radical-rebound reaction mechanism is analogous to the experimentally available MMOs with diamond Fe 2 O 2 core accompanied by a coordinate number of six for the hydroxylation of methane. The rate constants for the hydroxylation of substrates catalyzed by Q increase along CH 4 < CH 3 F < CH 3 CN CH 3 NO 2 < CH 3 CH 3 . Both the activation strain Δ E ≠ strain and the stabilizing interaction Δ E ≠ int jointly affect the activation energy Δ E ≠ . For the C-H cleavage of substrate CH 3 X, with the decrease of steric shielding for the substituted CH 3 X (X = F > H > CH 3 > NO 2 > CN) attacking the O center in Q, the activation strain Δ E ≠ strain decreases, whereas the stabilizing interaction Δ E ≠ int increases. It is predicted that the MMO with peroxo dizinc Zn 2 O 2 core should be a promising catalyst for the hydroxylation of methane and its derivatives. The theoretically designed methane monooxygenase with peroxo dizinc core showed promise for the hydroxylation of methane and its derivatives.