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Abstract: Lentinula edodes produces two laccases. One laccase (Lcc 1) is secreted into the culture medium of the vegetative mycelia, and the other (Lcc 2) accumulates in the gill tissue of fruiting bodies. The two enzymes are monomeric proteins with the molecular masses of 72 kDa (Lcc 1) and 58 kDa (Lcc 2). The substrate specificities of the two enzymes were determined. The conventional substrates of laccases, such as ABTS, guaiacol and 2,6-dimthoxyphenol, were oxidized by both enzymes. However, significant differences between Lcc 1 and Lcc 2 were found in their activities for catechol, ferulic acid, beta-(3,4- dihydroxyphenyl)alanine (DOPA) and 1,2,3-trihydroxy benzene. The decolorization activities of the two enzymes were determined using several chemically different dyes as substrates. Both enzymes decolorized seven different dyes without a mediator. The decolorization of nine dyes required a redox mediator, violuric acid. Comparing the decolorization activities of the two enzymes, Lcc 1 was more active than Lcc 2. Thus, we concluded that Lcc 1 was the enzyme of choice for use in the decolorization of wastewater from textile dyeing.
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