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Abstract

Copper-containing sites of laccases isolated from the Basidiomycetes Coriolus hirsutus and Coriolus zonatus were characterized by optical methods and EPR spectroscopy. Methods for preparation of fungal laccase derivatives free from type 2 copper ions were compared. The data of EPR spectroscopy and spectrophotometric titration of copper sites showed that only a modified method based on the use of bathocuproine as a chelator for type 2 copper yielded laccase derivatives completely free from type 2 copper. The original enzymes can be reconstituted from the derivatives by dialysis under anaerobic conditions, resulting in complete recovery of native conformation of the protein molecule and the structure of the copper-containing site.

Effect of the L499M mutation of the ascomycetousBotrytis acladalaccase on redox potential and catalytic properties

“…Both T3 copper ions are in a distorted tetrahedral coordination. The Cu2 ion can be selectively removed from laccase by treatment with chelating agents, resulting in the formation of the inactive T2 copperdepleted form of the enzyme (Reinhammar & Oda, 1979;Koroleva et al, 2001). The three-dimensional structures of several T2 copper-depleted laccases have been determined (Ducros et al, 1998(Ducros et al, , 2001De la Mora et al, 2012).…”

Interaction of Coal Humic Acids with Fungal Laccase

“…However, it is widely accepted that laccase can loose its activity because of dissociation of Cu only in the presence of a strong chelating agent under anaerobic conditions. Even for elimination of copper type 2 (the most easily eliminating copper ion from laccase) it is necessary to use guanidine chloride under denaturing condition followed by bathcuproine treatment [45,46]. In this study interaction of native laccase with HA under non-denaturing conditions has been carried out.…”

Biocathodes for Dioxygen Reduction in Biofuel Cells

“…For the majority of laccases the redox potential of the electron-accepting ENZYMES FOR DIOXYGEN REDUCTION CATALYSIS (b) active center of laccase containing 4 copper atoms (types T 1 , T 2 , and T 3 , from right to left) [19]. T 1 site is in the range 0.43-0.78 V versus NHE [20][21][22][23][24][25][26][27]. From this perspective, laccases can be divided into three groups: low-, medium-, and high-potential.…”

“…The intermediate ones with T 1 redox potential in the range 0.47-0.71 V versus NHE are isolated from fungi [21,29]. For the high-potential laccases the value is $0.78 V versus NHE [23,28]. Obviously, the latter group is most interesting for application in biocathodes.…”