Quantum Refinement Does Not Support Dinuclear Copper Sites in Crystal Structures of Particulate Methane Monooxygenase. Issue 1 (8th December 2017)

• Record Type: Journal Article
• Authors: Cao, Lili; Caldararu, Octav; Rosenzweig, Amy C.; Ryde, Ulf
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 1(2018)
• Page Start: 162
• Page End: 166
• Publication Date: 2017-12-08
• Subjects: copper -- density functional theory -- particulate methane monooxygenase -- quantum refinement; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201708977
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Particulate methane monooxygenase (pMMO) is one of the few enzymes that can activate methane. The metal content of this enzyme has been highly controversial, with suggestions of a dinuclear Fe site or mono‐, di‐, or trinuclear Cu sites. Crystal structures have shown a mono‐ or dinuclear Cu site, but the resolution was low and the geometry of the dinuclear site unusual. We have employed quantum refinement (crystallographic refinement enhanced with quantum‐mechanical calculations) to improve the structure of the active site. We compared a number of different mono‐ and dinuclear geometries, in some cases enhanced with more protein ligands or one or two water molecules, to determine which structure fits two sets of crystallographic raw data best. In all cases, the best results were obtained with mononuclear Cu sites, occasionally with an extra water molecule. Thus, we conclude that there is no crystallographic support for a dinuclear Cu site in pMMO. Abstract : Two crystal structures of particulate methane monooxygenase (pMMO) were studied with quantum refinement. For the putative active site, several different mono‐ and dinuclear geometries, in some cases with more protein ligands or one or two water molecules, were compared to determine which structure fits the crystallographic raw data best. The results indicate that there is no crystallographic support for a dinuclear Cu site in pMMO.