Summary: | In the present work crude <i>Agaricus bisporus</i> extract (ABE) has been prepared and characterized by its tyrosinase activity, protein composition and substrate specificity. The presence of mushroom tyrosinase (PPO3) in ABE has been confirmed using two-dimensional electrophoresis, followed by MALDI TOF/TOF MS-based analysis. GH27 alpha-glucosidases, GH47 alpha-mannosidases, GH20 hexosaminidases, and alkaline phosphatases have been also detected in ABE. ABE substrate specificity has been studied using 19 phenolic compounds: polyphenols (catechol, gallic, caffeic, chlorogenic, and ferulic acids, quercetin, rutin, dihydroquercetin, <span style="font-variant: small-caps;">l</span>-dihydroxyphenylalanine, resorcinol, propyl gallate) and monophenols (<span style="font-variant: small-caps;">l</span>-tyrosine, phenol, <i>p</i>-nitrophenol, <i>o</i>-nitrophenol, guaiacol, <i>o</i>-cresol, <i>m</i>-cresol, <i>p</i>-cresol). The comparison of ABE substrate specificity and affinity to the corresponding parameters of purified <i>A. bisporus</i> tyrosinase has revealed no major differences. The conditions for spectrophotometric determination have been chosen and the analytical procedures for determination of 1.4 × 10<sup>−4</sup>–1.0 × 10<sup>−3</sup> M <span style="font-variant: small-caps;">l</span>-tyrosine, 3.1 × 10<sup>−6</sup>–1.0 × 10<sup>−4</sup> M phenol, 5.4 × 10<sup>−5</sup>–1.0 × 10<sup>−3</sup> M catechol, 8.5 × 10<sup>−5</sup>–1.0 × 10<sup>−3</sup> M caffeic acid, 1.5 × 10<sup>−4</sup>–7.5 × 10<sup>−4</sup> M chlorogenic acid, 6.8 × 10<sup>−5</sup>–1.0 × 10<sup>−3</sup> M <span style="font-variant: small-caps;">l</span>-DOPA have been proposed. The procedures have been applied for the determination of <span style="font-variant: small-caps;">l</span>-tyrosine in food supplements, <span style="font-variant: small-caps;">l</span>-DOPA in synthetic serum, and phenol in waste water from the food manufacturing plant. Thus, we have demonstrated the possibility of using ABE as a substitute for tyrosinase in such analytical applications, as food supplements, medical and environmental analysis.
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