Purified particulate methane monooxygenase from Methylococcus capsulatus (Bath) is a dimer with both mononuclear copper and a copper-containing cluster

Raquel L. Lieberman, Deepak B. Shrestha, Peter E. Doan, Brian M. Hoffman, Timothy L. Stemmler*, Amy C. Rosenzweig

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

119 Scopus citations

Abstract

Particulate methane monooxygenase (pMMO) is a membrane-bound enzyme that catalyzes the oxidation of methane to methanol in methanotropic bacteria. Understanding how this enzyme hydroxylates methane at ambient temperature and pressure is of fundamental chemical and potential commercial importance. Difficulties in solubilizing and purifying active pMMO have led to conflicting reports regarding its biochemical and biophysical properties, however. We have purified pMMO from Methylococcus capsulatus (Bath) and detected activity. The purified enzyme has a molecular mass of ≈200 kDa, probably corresponding to an α2β2γ2 polypeptide arrangement. Each 200-kDa pMMO complex contains 4.8 ± 0.8 copper ions and 1.5 ± 0.7 iron ions. Electron paramagnetic resonance spectroscopic parameters corresponding to 40-60% of the total copper are consistent with the presence of a mononuclear type 2 copper site. X-ray absorption near edge spectra indicate that purified pMMO is a mixture of Cu(I) and Cu(II) oxidation states. Finally, extended x-ray absorption fine structure data are best fit with oxygen/nitrogen ligands and a 2.57-Å Cu-Cu interaction, providing direct evidence for a copper-containing cluster in pMMO.

Original languageEnglish (US)
Pages (from-to)3820-3825
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume100
Issue number7
DOIs
StatePublished - Apr 1 2003

ASJC Scopus subject areas

  • General

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