Laccase properties

Yaropolov, A.I., Skorobogat ko, O.V., Vartanov, S.S., and Varfolomeyev, S.D. 1994. Laccase Properties, catalytic mechanism, and applicability. Appl. Biochem. Biotechnol. 49 257-280. 

Figure 2.3. Hypothetical mechanism of ligninocellulose transformation by enzymes of white-rot fungi. The initial products of partial wood hydrolysis distinctly induce enzymatic systems accelerating the degradation processes. Reprinted from Leonowicz, A., Cho, N.-S., Luterek, I, et al. (2001). Fungal laccase properties and activity on lignin./. Basic Microbiol. 41,185-227, with permission from Wiley-VCH.

Superoxide anion scavenging activity of the enzymatically synthesized poly(catechin) was evaluated. Poly(catechin), synthesized by HRP catalyst, greatly scavenged superoxide anion in a concentration-dependent manner, and almost completely scavenged at 200 p.M of a catechin unit concentration. The laccase-catalyzed synthesized poly(catechin) also showed excellent antioxidant property. Catechin showed pro-oxidant property in concentrations lower than 300 jlM. These results demonstrated that the enzymatically synthesized poly(catechin) possessed much higher potential for superoxide anion scavenging, compared with intact catechin. 

Felby C, Hassingboe J and Lund M. 2002. Pilot-scale production of fiberboards made by laccase oxidized wood fibers board properties and evidence for cross-linking of lignin. Enzyme Microb Technol 31(6) 736—741. 

Micard V and Thibault JF. 1999. Oxidative gelation of sugar-beet pectins use of laccases and hydration properties of the cross-linked pectins. Carbohyd Polym 39 265-273. 

Table 5.2 contains data about selected copper enzymes from the references noted. It should be understood that enzymes from different sources—that is, azurin from Alcaligenes denitrificans versus Pseudomonas aeruginosa, fungal versus tree laccase, or arthropodan versus molluscan hemocyanin—will differ from each other to various degrees. Azurins have similar tertiary structures—in contrast to arthropodan and molluscan hemocyanins, whose tertiary and quaternary structures show large deviations. Most copper enzymes contain one type of copper center, but laccase, ascorbate oxidase, and ceruloplasmin contain Type I, Type II, and Type III centers. For a more complete and specific listing of copper enzyme properties, see, for instance, the review article by Solomon et al.4... 

This discussion of copper-containing enzymes has focused on structure and function information for Type I blue copper proteins azurin and plastocyanin, Type III hemocyanin, and Type II superoxide dismutase s structure and mechanism of activity. Information on spectral properties for some metalloproteins and their model compounds has been included in Tables 5.2, 5.3, and 5.7. One model system for Type I copper proteins39 and one for Type II centers40 have been discussed. Many others can be found in the literature. A more complete discussion, including mechanistic detail, about hemocyanin and tyrosinase model systems has been included. Models for the blue copper oxidases laccase and ascorbate oxidases have not been discussed. Students are referred to the references listed in the reference section for discussion of some other model systems. Many more are to be found in literature searches.50... 

Copper, like iron, is frequently encountered in reactions involving dioxygen. The copper enzyme laccase catalyses the oxidation of uroshiol (the same poisonous substance found in poison oak and ivy) in the production of Japanese lacquer. It is the products of uroshiol oxidation, which are responsible for the lacquer s remarkable material properties. 

Barsberg and Hassingboe (2003) noted that the use of enzymes for surface activation of fibres for board production can produce highly variable results and that the reasons for this are not understood. In order to further understand the process, they treated TMP fibres with a laccase from Trametes villosa for 1 hour and dried the fibres. A control set of fibres was subjected to an identical protocol, but with no enzyme present. Air-laid fibre mats were produced from the fibres, which were then hot-pressed to form 3 mm thickness boards. Varying amounts of wax were sprayed on to the fibres prior to board production. Both the MOE and the MOR of the composites increased with board density. Boards produced from enzyme-treated or control fibres exhibited no difference in MOE, but the MOR of boards formed from enzyme-treated fibres was higher above a density of 800 kg m . Wax addition resulted in a decrease in mechanical properties. At a board density of c. 930 kg m , the MOR was of the order of 23 MPa and the MOE 11 GPa. 

Barsberg, S. and Thygesen, L.G. (1999). Spectroscopic properties of oxidation species generated in the lignin of wood fibres by a laccase catalysed treatment electronic hole state migration and stabilization in the lignin matrix. Biochimica et Biophysica Acta, 1472, 625-642. 

It should be noted that some commercial enzyme preparations may contain several enzyme isomers (enzymes derived from one source which belong to the same enzyme class but differ in specificity, stability or other properties). This is most often the case when the commercial preparation was developed for a process industry application rather than a specific chemical biotransformation application. Some fungal enzymes, such as laccase, are sometimes supplied as crude enzyme mixtures. Fungal laccases are manufactured on a huge scale (multitonne per annum) and are principally used in bulk processes such as wood... 

Reduction of the met derivatives by one electron produces the mixed-valent 1/2-met (Cu(II)Cu(l)] derivatives. A comparison of the chemical and spectroscopic properties of 1/2-met hemocyanln and 1/2-met T2D laccase reveals a number of important differences (Figure 12). 

The enzyme properties reported above are similar to those of an aromatic alcohol oxidase from Polystictus versicolor (27). However, the latter enzyme had a different substrate specificity and the cultures did not produce laccase. 

Laccase, 36 318, 329, 40 122 see also Blue copper oxidases amino-acid sequences, 40 141 anaerobic reduction, 40 158-160 biological function, 40 124 electrochemistry, 36 360 fungal, 40 145-152 evolution, 40 153-154 inhibition, 40 162 kinetic properties, 40 157-162 molecular and spectroscopic properties, 40 125-126... 

Application of Laccase as a Radical Donor in Adhesives for Particle Boards. The properties of laccase with regard to lignin render it a candidate for application in technical processes. A two-component adhesive was formulated with lignin as the phenolic component and laccase as radical donor. The process is described in more detail elsewhere (1). 

Baldrian, P. (2006). Fungal laccases—Occurrence and properties. FEMS Microbiol. Rev. 30, 215-242. 

Dubernet, M., Ribereau-Gayon, P., Lerner, H. R., Harel, E. And, and Mayer, A. M. (1977). Purification and properties of a laccase from Botrytis cinerea. Phytochemistry 16,191-193. 

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