Enzymatic removal of various phenol compounds from artificial wastewater was undertaken by the combined use of mushroom tyrosinase (EC 1.14.18.1) and chitosan beads as function of pH value, temperature, tyrosinase dose, and hydrogen peroxide-to-substrate ratio. Chitosan film incubated in a p-crersol+tyrosinase mixture had the main peaks at 400-470 nm assigned to chemically adsorbed quinone derivatives, which increased over the immersion time. These results indicate that removal of phenol compounds is caused by their tyrosinase-catalyzed oxidation to the corresponding quinone derivatives and the subsequent chemical adsorption on the chitosan film. The optimum conditions for quinone adsorption were determined to be pH 7 and 45 degrees C for p-cresol. Some alkyl-substituted phenol compounds were removed by adsorption of quinone derivatives enzymatically generated on the chitosan beads, and the % removal for p-cresol, 4-ethylphenol, 4-n-propylphenol, 4-n-butylphenol, and p-chlorophenol went up to 93%. In addition, 4-tert-butylphenol underwent tyrosinase-catalyzed oxidation in the presence of hydrogen peroxide. This procedure was applicable to removal of chlorophenols and alkyl-substituted phenols.

A novel programmable membrane fusion system driven by selective molecular recognition between diols and boronic acids on the different vesicles was constructed in this study.

Enzymatic removal of p-alkylphenols from aqueous solutions was investigated through the two-step approach, the quinone conversion of p-alkylphenols with mushroom tyrosinase (EC 1.14.18.1) and the subsequent adsorption of quinone derivatives enzymatically generated on chitosan beads at pH 7.0 and 45 degrees C as the optimum conditions. This technique is quite effective for removal of various p-alkylphenols from an aqueous solution. The % removal values of 97-100% were obtained for p-n-alkylphenols with carbon chain lengths of 5 to 9. In addition, removal of other p-alkylphenols was enhanced by increasing either the tyrosinase concentration or the amount of added chitosan beads, and their % removal values reached >93 except for 4-tert-pentylphenol. This technique was also applicable to remove 4-n-octylphenol (4NOP) and 4-n-nonylphenol (4NNP) as suspected endocrine disrupting chemicals. The reaction of quinone derivatives enzymatically generated with the chitosan's amino groups was confirmed by the appearance of peaks for UV-visible spectrum measurements of the chitosan films incubated in the p-alkylphenol and tyrosinase mixture solutions. In addition, 4-tert-pentylphenol underwent tyrosinase-catalyzed oxidation in the presence of hydrogen peroxide.