Blue multicopper oxidases (MCOs) including bilirubin oxidase are enzymes catalyzing oxidation of a substrate accompanied by four electron reduction of molecular oxygen to two molecules of water. Electrons taken from the substrate are transported from the oxidation center, containing copper ion as an electron acceptor, through a highly conserved motive – cysteine‑histidine bridge to a reduction center, where they are utilized for oxygen reduction .
Bilirubin oxidase from plant pathogen Myrothecium verrucaria (MvBO, EC 126.96.36.199) catalyzes oxidation of a great variety of compounds (e.g. bilirubin to biliverdin) with the use of oxygen as a second substrate, where no hydrogen peroxide comes out of the reaction. Therefore, it is interesting for many industrial applications such as pulp bleaching, delignification or development of biosensors and experimental biofuel technology .
Although the complete crystal structure of MvBO has been already published (PDB code: 2XLL , 3ABG ), the mechanism of substrate binding and the way of the electron transport from substrate to the oxidation center still need explanation. On the basis of our latest results, we are able to suggest possible ways of electron transfer from the substrate to the oxidation center.
This work is supported by the project "BIOCEV - Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University (CZ.1.05/1.1.00/02.0109), from the ERDF, by the Ministry of Education, Youth and Sports of the Czech Republic (grant No. LG14009) and by the Grant Agency of the Czech Technical University in Prague, grant No. SGS16/246/OHK4/3T/14.