title: Which copper is paramagnetic in the type 2/type 3 cluster of laccase?
abstract: Understanding the structure and function of the three copper atoms in the dioxygen reduction site of the blue oxidases such as laccase has been a long standing challenge. In the case of a widely studied derivative, known as type 2-depleted laccase, the removal of one copper from the cluster abolishes the EPR signal of the so-called type 2 copper. However, the present studies of isotopically enriched protein from Polyporus versicolor show that the readily replaceable copper is not active in the low-temperature EPR spectrum of fungal laccase or its difluoride adduct. The same is true for the difluoride adduct of the tree enzyme. Thus, in type 2-depleted laccase the pattern of antiferromagnetic coupling is quite different from that of the native protein or the difluoride adduct.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393, USA.
authors.forename: T L
authors.initials: TL
authors.lastname: Fraterrigo
authors.forename: C
authors.initials: C
authors.lastname: Miller
authors.forename: B
authors.initials: B
authors.lastname: Reinhammar
authors.forename: D R
authors.initials: DR
authors.lastname: McMillin
mesh_terms: D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005459:Fluorides; D042845:Laccase; D008280:Magnetics; D010088:Oxidoreductases / Q000737:chemistry*; D011124:Polyporaceae / Q000201:enzymology*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003300:Copper; D010088:Oxidoreductases; D042845:Laccase; D005459:Fluorides