title: Direct bio-electrocatalysis of O2 reduction by Streptomyces coelicolor laccase orientated at promoter-modified graphite electrodes.
abstract: Bacterial laccase from Streptomyces coelicolor (SLAC) has been immobilised and orientated at promoter (pyrene and neocuproine)-modified electrodes productively both for direct electron transfer (ET) between the electrode and the T1 Cu site of SLAC and direct (unmediated) bio-electrocatalysis of dioxygen reduction. Its T1 Cu potential ranges between 471 and 318 mV versus the normal hydrogen electrode, at pH 5.5 and 8, respectively; this value is dependent both on the solution pH and electrode modification. In the presence of O2, Cu of the T2/T3 trinuclear centre is distinguished electrochemically at 748-623 mV. Depending on the promoter nature, different orientations of SLAC at pyrene- and neocuproine-modified electrodes can be followed from the kinetic analysis of the ET rates. Bio-electrocatalytic reduction of oxygen starts from the T1 Cu potentials of SLAC, and is most efficient at the promoter-modified electrodes, thereby demonstrating good performance both in neutral and basic media and in solutions with a high NaCl content, such as sea water. The obtained results allow consideration of a broader bioenergetic application of laccases as biocathodes operating directly in such environmental media as sea water and physiological fluids.
authors.affiliation: Interdisciplinary Nanoscience Center, Science and Technology, Aarhus University, Gustav Wieds Vej 1590-14, 8000 Aarhus C, Denmark.
authors.forename: Samuel
authors.initials: S
authors.lastname: Lörcher
authors.forename: Paula
authors.initials: P
authors.lastname: Lopes
authors.forename: Andrey
authors.initials: A
authors.lastname: Kartashov
authors.forename: Elena E
authors.initials: EE
authors.lastname: Ferapontova
mesh_terms: D055162:Biocatalysis; D055664:Electrochemical Techniques; D004566:Electrodes; D006108:Graphite / Q000737:chemistry / Q000378:metabolism*; D042845:Laccase / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*; D048372:Streptomyces coelicolor / Q000201:enzymology*; D013499:Surface Properties
chemical_list: D006108:Graphite; D042845:Laccase; D010100:Oxygen
keywords: bioelectrocatalysis; electron transfer; enzymes; fuel cells; oxygen