Characterization of the biocatalysis of tyrosinase in selected organic solvent media using model phenolic substrates

Mushroom tyrosinase biocatalysis in selected organic solvent media, including dichloromethane and heptane, was investigated using phenolic model substrates including catechin, catechol, 4-methyl catechol, and p-cresol. Vmax values for tyrosinase biocatalysis in dichloromethane for 4-methyl catechol, catechol, and catechin were 5.07×10−4, 6.03×10−4 and 1.47×10−3 δA/(μg protein s), respectively, while the Km values were 2.21, 2.36 and 2.52 mM, respectively. In heptane, tyrosinase showed Vmax values of 0.84×10−4, 1.02×10−4, and 1.22×10−3 δA/(μg protein s) with p-cresol, catechol and catechin, respectively, with corresponding Km values of 1.07, 4.32 and 5.38 mM. The characterization of the oxidation products resulting from the reactions of tyrosinase with selected substrates was carried out by spectrophotometeric scanning, differential scanning calorimetry and pyrolysis/gas chromatography coupled to mass spectrometry. The results showed that the change in reaction medium resulted in the formation of oxidation products that differed with respect to their maxima absorbance, thermal parameters and wide range of pyrolysis residues.