Large Scale ab Initio Quantum Chemical Calculation of the Intermediates in the Soluble Methane Monooxygenase Catalytic Cycle

Autor:	Michael D. Beachy, Yixiang Cao, Barry D. Dunietz, Stephen J. Lippard,‡ and, Richard A. Friesner, Douglas A. Whittington
Rok vydání:	2000
Předmět:	biology Hydrogen Hydrogen bond Methane monooxygenase Ab initio Active site chemistry.chemical_element General Chemistry Biochemistry Catalysis Colloid and Surface Chemistry chemistry Catalytic cycle Computational chemistry biology.protein Molecule
Zdroj:	Journal of the American Chemical Society. 122:2828-2839
ISSN:	1520-5126 0002-7863
DOI:	10.1021/ja9920967
Popis:	Ab initio DFT quantum chemical methods are applied to study intermediates in the catalytic cycle of soluble methane monooxygenase hydroxylase (MMOH), a dinuclear iron-containing enzyme that converts methane and dioxygen selectively to methanol and water. The quantum chemical models reproduce reliably the X-ray crystallographic coordinates of the active site for the oxidized diiron(III) and reduced diiron(II) states to a high degree of structural precision. The results inspired a reexamination of the X-ray structure of reduced MMOH and revealed previously unassigned electron density now attributed to a key structural water molecule. The quantum chemical calculations required construction of a model containing about 100 atoms, which preserved key hydrogen bonding patterns necessary for structural integrity. Smaller models were unstable for the reduced form of the enzyme, an observation with significant mechanistic implications. The large model was then used to investigate the catalytic intermediates Hperoxo...
Databáze:	OpenAIRE
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