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Direct Bio‐electrocatalysis of O 2 Reduction by Streptomyces coelicolor Laccase Orientated at Promoter‐Modified Graphite Electrodes
Author(s) -
Lörcher Samuel,
Lopes Paula,
Kartashov Andrey,
Ferapontova Elena E.
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300069
Subject(s) - electrocatalyst , streptomyces coelicolor , electrode , chemistry , laccase , pyrene , electron transfer , inorganic chemistry , electrochemistry , photochemistry , organic chemistry , biochemistry , enzyme , mutant , gene
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 O 2 , 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.