Novel Basidiomycetous Alcohol Oxidase from Cerrena unicolor—Characterisation, Kinetics, and Proteolytic Modifications

Intracellular alcohol oxidase (AOX) was isolated from the basidiomycetous white rot fungus <i>Cerrena unicolor</i> FCL139. The enzyme was semi-purified (13-fold) using two-step chromatography with 30% activity recovery. The identity of the protein was confirmed by LC-MS/MS analysis, and its MW (72 kDa) and pI (6.18) were also determined. The kinetics parameters of the AOX reaction towards various substrates were analysed, which proved that, in addition to methanol (4.36 ± 0.27% of the oxidised substrate), AOX most potently oxidises aromatic alcohols, such as 4-hydroxybenzyl alcohol (14.0 ± 0.8%), benzyl alcohol (4.2 ± 0.3%), anisyl alcohol (7.6 ± 0.4%), and veratryl alcohol (5.0 ± 0.3%). Moreover, the influence of selected commercially available proteases on the biocatalytic properties of AOX from <i>C. unicolor</i> was studied. It was proved that the digested enzyme lost its catalytic potential properties except when incubated with pepsin, which significantly boosted its activity up to 123%.