Purification and characterization of a thermostable laccase with unique oxidative characteristics from Trametes hirsuta

Abstract

A laccase was purified from Trametes hirsuta. This laccase was classified as a "white" or "yellow" laccase. pH 2.4 was optimal for the oxidation of ABTS and pH 2.5 for DMP. DMP oxidation was optimal at 85 degrees C. The half-life of this laccase was 70 min at 75 degrees C, and 5 h at 65 degrees C. Non-phenolic dyes, such as Methyl Red, were oxidized by purified laccase without mediators. The enzyme was not inhibited by Cu(2+), Mn(2+), or EDTA. These are atypical laccase characteristics that make it a good candidate for theoretical and applied research.

An extracellular laccase with potent dye decolorizing ability from white rot fungus Trametes sp. LAC-01

“…HYB07 and laccase from R. virescens aslo demonstrated decoloring activity toward the two dyes [28,30]. T. hirsuta laccase was reported to demonstrate decolorizing ability toward non-phenolic dyes, such as Methyl Red [58]. Laccase from P. sanguineus BRFM 66 also possessed considerably high decolorization activity toward Anthraquinonic Dye Poly R-478 (33%) and Heterocyclic Dye Azure B (21%) after 52 h of incubation [50].…”

Laccases: a never-ending story

“…The enzyme contains only one copper atom/molecule instead of the usual four, along with two zinc atoms and one iron atom in each protein molecule. Other so-called white laccases were purified from Pycnoporous sanguineus [135], from T. hirsuta [136], and from P. radiata BP-11-2 [137]. The analysis of metal ion contents of the laccase from T. hirsuta has shown the presence of copper and manganese in a 3:1 ratio.…”

Expression, refolding, and characterization of a small laccase from Thermus thermophilus HJ6

“…The purified 35 enzyme exhibited the laccase activity with the optimal catalytic temperature at 75°C. The optimum 36 pH for the oxidation of 2,2 0 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and syringaldazine 37 was 4.5 and 6.0, respectively. The recombinant protein showed high thermostability, and the half-life of 38 heat inactivation was about 50 min at 85°C.…”