Chemical Modifications of Laccase from White-Rot Basidiomycete Cerrena unicolor

Abstract

Laccases belong to the group of phenol oxidizes and constitute one of the most promising classes of enzymes for future use in various fields. For industrial and biotechnological purposes, laccases were among the first enzymes providing larger-scale applications such as removal of polyphenols or conversion of toxic compounds. The wood-degrading basidiomycete Cerrena unicolor C-139, reported in this study, is one of the high-laccase producers. In order to facilitate novel and more efficient biocatalytic process applications, there is a need for laccases with improved biochemical properties, such as thermostability or stability in broad ranges of pH. In this work, modifications of laccase isoforms by hydrophobization, hydrophilization, and polymerization were performed. The hydrophobized and hydrophilized enzyme showed enhanced surface activity and higher ranges of pH and temperatures in comparison to its native form. However, performed modifications did not appear to noticeably alter enzyme’s native structure possibly due to the formation of coating by particles of saccharides around the molecule. Additionally, surface charge of modified laccase shifted towards the negative charge for the hydrophobized laccase forms. In all tested modifications, the size exclusion method led to average 80 % inhibition removal for hydrophilized samples after an hour of incubation with fluoride ions. Samples that were hydrophilized with lactose and cellobiose showed an additional 90 % reversibility of inhibition by fluoride ions after an hour of concluding the reaction and 40 % after 24 h. The hydrophobized laccase showed higher level of the reversibility after 1 h (above 80 %) and 24 h (above 70 %) incubation with fluoride ions. The addition of ascorbate to laccase solution before a fluoride spike resulted in more efficient reversibility of fluoride inhibitory effect in comparison to the treatments with reagents used in the reversed sequence.

Effective and complex stimulation of the biodegradation system of fungus Cerrena unicolor by rapeseed meal fermentation

“…Moreover, dif- ferences in the molecular weight of the laccase in the cultures stimulated with RM compared with the control may result from quantitative and qualitative differences in the carbohydrate content of the enzyme molecule. The characterization of glycosylation of C. unicolor laccase isoenzymes was described in the previous paper (Kucharzyk et al, 2012;Lisova et al, 2010). The fact that the enzyme is secreted mostly in the form of isoenzymes was confirmed by the presented studies (Majeau et al, 2010).…”

Bacterial exopolysaccharides as a modern biotechnological tool for modification of fungal laccase properties and metal ion binding

“…It is known that one of the difficulties in the use of the enzyme in the industry is to keep its storage operative stability [49]. Therefore, numerous studies on laccase stability, both by the chemical modification of the enzyme molecule and by modifying the reaction conditions and the environment are conducted [23, 50, 51]. …”

“…Kucharzyk et al studied the effects of chemical modifications of laccase, using hydrophobization, hydrophilization, and polymerization, on the thermostability of the enzyme and its stability in a wide pH range [23]. One of such modifications may be the addition of some chemicals to the reaction, which increase enzyme stability and activity.…”

Laccase purified from Cerrena unicolor exerts antitumor activity against leukemic cells

“…Cerrena unicolor has been established as the most effective fungal source of extracellular (ex)-LAC, with the highest activity reported to be 60,000 nkat/l ( 14 ). C. unicolor ex-LAC has been utilized in biodegradation, bioremediation, delignification and decolorization, although no data regarding its anticancer activity have been published to date ( 15 ).…”