Recombinant tyrosinase from Polyporus arcularius: overproduction in Escherichia coli, characterization and use in a study of aurones as tyrosinase  
E. Böhmová, M. Kotík, A. Křenková, P. Man, R. Haudecoeur, A. Boumendjel, R. Hardre, Y. Mekmouche, E. Courvoisier-Dezord, M. Réglier, L. Martínková
J. Agric. Food Chem. 64, 2925-2931.
The aims of this study were to examine the expression of a fungal tyrosinase gene in a prokaryotic host and to use the enzyme as a model of a eukaryotic tyrosinase. Specifically, the effects of various aurones (tyrosinase inhibitors, activators or substrates) on the enzyme were tested. The pro-tyrosinase from Polyporus arcularius was produced in Escherichia coli, partially purified in a Ni-affinity column and activated by trypsin-catalyzed removal of its C-terminal part. Trypsin cleaved the pro-tyrosinase after the R388 residue according to MALDI-TOF analysis of the active enzyme purified by size-exclusion chromatography. This enzyme was a homodimer and transformed L-DOPA (Km = 1.04 ± 0.08 mM, kcat = 223 ± 8 s-1), tert-butylcatechol, L-tyrosine, p-cresol, phenol and 4’- hydroxyaurones. 3’- and 2’-Hydroxyaurones acted as activators and 2’,4’-dihydroxyaurone as an inhibitor. The enzyme is a promising model for tyrosinase effector studies, being, in contrast to the commercial tyrosinase, a single isoenzyme.