Electrocatalysis of a Europium‐Dependent Bacterial Methanol Dehydrogenase with Its Physiological Electron‐Acceptor Cytochrome c_GJ

Abstract

We report the first electrochemical study of al anthanoid-dependent methanold ehydrogenase (Eu-MDH) from the acidophilic verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV with its own physiological cytochrome c GJ electron acceptor.E u-MDH harbours ar edox active 2,7,9-tricarboxypyrroloquinoline quinone( PQQ) cofactor which is non-covalently bound but coordinates trivalent lanthanoid elements including Eu 3 + .E u-MDH and the cytochromew ere co-adsorbed with the biopolymerc hitosan and cast onto am ercaptoundecanol (MU) monolayer modified Au working electrode.C yclic voltammetry of cytochrome c GJ reveals aw ell-definedq uasi-reversible Fe III/II redox couple at + 255 mV vs. NHEa tp H7.5 and this response is pH independent. The reversible one-electronr esponseo ft he cytochrome c GJ transformsi nto as igmoidal catalytic wave in the presence of Eu-MDH and its substrates (methanol or formaldehyde). The catalyticc urrentw as pH-dependent and pH 7.3 was found to be optimal. Kinetic parameters (pHd ependence,a ctivation energy) obtained by electrochemistry show the same trends as those obtained from an artificial phenazine ethosulfate/dichlorophenol indophenol assay.[a] Dr.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.

Neodymium as Metal Cofactor for Biological Methanol Oxidation: Structure and Kinetics of an XoxF1-Type Methanol Dehydrogenase

“…5D ). These values are similar to previously reported values of the europium-containing XoxF2 from Methylacidiphilum fumariolicum SolV ( 53 ).…”

The Chemistry of Lanthanides in Biology: Recent Discoveries, Emerging Principles, and Technological Applications

“…Few enzymes, and particularly redox enzymes, are active with more than one or two different metal cofactors. , Design of an enzyme that can tolerate several lanthanides in the same protein framework is a challenge because of differences in Ln III ionic radius and CN preference as well as interactions with substrate and intermediates, which may affect the methanol oxidation chemistry . Furthermore, in vivo, the electrons extracted from methanol to the Ln III -PQQ cofactor must then be transferred to XoxG, ,, and the efficiency of this process would be expected to depend on the identity of the Ln III ion coordinated by PQQ …”

Isolation and Characterization of Homologically Expressed Methanol Dehydrogenase from Methylorubrum extorquens AM1 for the Development of Bioelectrocatalytical Systems

“…In another work [ 25 ], MDH from Methylobacterium nodulans was immobilized on the graphite paste electrode for amperometric determination of methanol concentration in presence of the electron transport mediator, ferrocene. The electrochemical oxidation of methanol and formaldehyde catalyzed by Eu 3+ -MDH with its own native cytochrome electron acceptor, c GJ , co-adsorbed by chitosan biopolymer, was studied in the work [ 26 ]. It is known that the most sensitive biosensing systems based on PQQ-dehydrogenases are developed using ferrocene and its derivatives as electron transfer mediators [ 51 , 52 ].…”

“…MDH is known to manifest in vitro activity in presence of phenazine methosulfate (PMS) or phenazine ethosulfate towards artificial electron acceptors (2,6—dichlorophenolindophenol, 1,6-dichlorophenolindophenol, Wurster’s blue (N,N,N’,N’-tetramethyl-п-phenylenediamine and 2,2′-azino-(-3-ethylbenzthiazoline-6-sulfuric acid)), which are able to receive electrons from the reduced PQQ-enzyme [ 21 ]. This fact is the rationale for the application of PQQ-MDH in the development of electrochemical biosensors and biofuel cells (BFCs) [ 22 , 23 , 24 , 25 , 26 ]. In these works, only native methanol dehydrogenases were used.…”