Bacterial laccases

Within research on utilization of enzymatic processes for fibre extraction two preparations of different bacterial laccases (NS 51002 and NS 51003) were used and the third enzyme used was Pectinex 1OOL. The laccases are oxidoreductases which react directly with oxygen it is an important oxidant used in the paper industry to eliminate lignin from the pulp. 

Several directed evolution studies of bacterial laccase CotA have successfully improved its substrate specificity and functional expression, modifying its specificities by screening mutant libraries through surface display [33-37]. The advantages of some bacterial laccases include high thermostability and activity at neu-tral/alkaline pH, although a low-redox potential at the T1 site often precludes their use in certain sectors. 

Martins LO, Soares CM, Pereira MM, Teixeira M, Costa T, Jones GH, Henriques AO. Molecular and biochemical characterization of a highly stable bacterial laccase that occurs as a structural component of the Bacillus subtilis endospore coat. J Biol Chem 2002 277 18849-18859. 

Laccase was first isolated by Yoshida in 1883 [43] from tree lacquer of Rhus ver-nicifera. Laccases can thus be classified according to their source plant, fungal or, more recently, bacterial or insect [44], The laccase enzyme active site contains four copper ions classified into three types based upon their geometry and coordinating ligands, denoted... 

Bacterial hosts are inappropriate choices for expression of proteins such as the blue copper proteins stellacyanin, laccase, and ceruloplasmin which are extensively glycosylated. In these cases, it may be necessary to employ tissue cultures of appropriate origin to obtain the native protein. In this regard, the amino-terminal half of human serum transferrin, which lacks carbohydrate, has been expressed in high yield in baby hamster kidney cells by Funk et al. [13], while the glycosylated carboxyl-terminus has proved to be more problematic [103]. 

We illustrate these aspects of metalloprotein dynamics at surfaces by two specific proteins. One is the two-centre bacterial di-heme protein cyt c4 from Pseudomonas stutzeri, and the other is the fungal four-centre redox enzyme laccase from Polyporus versicolor. 

Laccase was used to coat flax fibers. The enzymatic treatment of lignocellulosic surface of the fibers was examined in the presence of various phenols [107]. Bacterial growth of Bacillus subtilis and Staphylococcus aureus was reduced significantly using ferulic acid. 

Laccase, ascorbate oxidase, and ceruloplasmin are the classical members of the multicopper oxidase family also known as blue oxidases. Recently, a small number of bacterial members of this family have been characterized, including CueO from E. coli a spore-coat laccase (CotA) from Bacillus suhtilis and phenoxazinone synthase from Streptomyces antibioticus The catalyzed reaction of these enzymes except for phenoxazinone synthase is given in Equation (11). A comprehensive overview of the broad and active research on blue copper oxidases is presented in Messerschmidt. Recent results have been included in a review on the reduction of dioxygen by copper-containing enzymes. The nature and number of the different copper sites in blue oxidases has been described in the sections about the type-1 copper site and the trinuclear copper cluster. 

Alternative methods have been sought to both shorten and provide more objective evaluation of rot. Such methods have included identification and quantification of key indicator metabolites of mold (laccase and/or glycerol), bacterial (acetic acid), and native yeast (ethanol) activity. 

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