title: Co2+/Co+ redox tuning in methyltransferases induced by a conformational change at the axial ligand.
abstract: Density functional theory and quantum mechanics/molecular mechanics computations predict cob(I)alamin (Co(+)Cbx), a universal B(12) intermediate state, to be a pentacoordinated square pyramidal complex, which is different from the most widely accepted viewpoint of its tetracoordinated square planar geometry. The square pyramidality of Co(+)Cbx is inspired by the fact that a Co(+) ion, which has a dominant d(8) electronic configuration, forms a distinctive Co(+)--H interaction because of the availability of appropriately oriented filled d orbitals. This uniquely H-bonded Co(+)Cbx may have catalytic relevance in the context of thermodynamically uphill Co(2+)/Co(+) reduction that constitutes an essential component in a large variety of methyltransferases.
authors.affiliation: Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
authors.forename: Manoj
authors.initials: M
authors.lastname: Kumar
authors.forename: Neeraj
authors.initials: N
authors.lastname: Kumar
authors.forename: Hajime
authors.initials: H
authors.lastname: Hirao
authors.forename: Pawel M
authors.initials: PM
authors.lastname: Kozlowski
mesh_terms: D002384:Catalysis; D002412:Cations / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry*; D008024:Ligands; D008780:Methyltransferases / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011789:Quantum Theory; D013816:Thermodynamics; D014805:Vitamin B 12 / Q000737:chemistry*
chemical_list: D002412:Cations; D008024:Ligands; D003035:Cobalt; D008780:Methyltransferases; D014805:Vitamin B 12