Versatile peroxidases

Although the exact mechanism of degradation at metabolic level for each compound or group of compounds is not well known, the involvement of extracellular oxidative enzymes such as LAC, MnP, LiP, and versatile peroxidase (VP) (see Tables 1 and 2 of Chap. 6) and intracellular monooxygenases as cytochrome P-450 is well documented for pollutants such as hydrocarbons, dyes, and halogenated solvents [25]. To determine the actual role of the extracellular enzymes, many studies are performed in vitro experiments with purified enzymes. In the case of cytochrome P-450, usually inhibitors are used. 

White-rot fungi produce three peroxidases that are involved in lignin degradation, namely, lignin peroxidase (LiP) and manganese peroxidase (MnP), first discovered in Phanerochaete chrysosporium in the 1980s, and versatile peroxidase (VP),... 

Class II Manganese, Lignin Peroxidases, and Versatile Peroxidases. 23... 

Fig. 2.11 Phylogeny of Class II of the peroxidase-catalase superfamily. Sequences coding for secretory fungal peroxidases lignin peroxidase (LiP), manganese peroxidase (MnP), and versatile peroxidase (VP) were used for this reconstruction. One of nine equally parsimonious trees is presented. Bootstrap values are indicated before slash, and Bayesian posterior probability values are indicated after the slash. With kind permission from Springer Science Business Media Morgenstem et al. [32], Fig. 2...

Ruiz-Duenas FJ, Morales M, Garcia E et al (2009) Substrate oxidation sites in versatile peroxidase and other basidiomycete peroxidases. J Exp Bot 60 441 152... 

Ruiz-Duenas FJ, Morales M, Perez-Boada M et al (2007) Manganese oxidation site in Pleurotus eryngii versatile peroxidase A site-directed mutagenesis, kinetic and crystallographic study. Biochemistry 46 66-77... 

Rodriguez E, Nuero O, Guillen F et al (2004) Degradation of phenolic and non-phenolic aromatic pollutants by four Pleurotus species the role of laccase and versatile peroxidase. Soil Biol Biochem 36 909-916... 

Davila-Vazquez G, Tinoco R, Pickard MA et al (2005) Transformation of halogenated pesticides by versatile peroxidase from Bjerkandera adusta. Enzyme Microb Technol 36 223-231... 

Perez-Boada M, Ruiz-Duenas FJ, Pogni R et al (2005) Versatile peroxidase oxidation of high redox potential aromatic compounds Site-directed mutagenesis, spectroscopic and... 

Pogni R, Baratto MC, Teutloff C et al (2006) A tryptophan neutral radical in the oxidized state of versatile peroxidase from Pleurotus eryngii a combined multi-frequency EPR and DFT study. J Biol Chem 281 9517-9526... 

Ruiz-Duenas FJ, Pogni R, Morales M et al (2009) Protein radicals in fungal versatile peroxidase catalytic tryptophan radical in both Compound I and Compound II and studies on W164Y, W164H and W164S variants. J Biol Chem 284 7986—7994... 

Moreira PR, Almeida-Vara E, Malcata EX et al (2007) Lignin transformation by a versatile peroxidase from a novel Bjerkandera sp strain. Int Biodeterior Biodegrad 59 234—238... 

Tsukihara T, Honda Y, Sakai R et al (2008) Mechanism for oxidation of high-molecular-weight substrates by a fungal versatile peroxidase, MnP2. Appl Environ Microbiol 74 2873-2881... 

Ruiz-Duenas FJ, Morales M, Mate MJ et al (2008) Site-directed mutagenesis of the catalytic tryptophan environment in Pleurotus eryngii versatile peroxidase. Biochemistry 47 1685-1695... 

The two-electron reduction of Compound I to Fe(III) and the one electron reduction of Compound I to Compound II and Compound II to Fe(III) have been estimated by different methods. These methods will be described in the next section, but they differ in the strategy to estimate the redox potential. Two of them rely on spectral determination of equilibrium between redox species [63-65], whereas a third one proposes the use of catalytic measurements [53]. The values obtained with the different methods are shown in Table 4.4. It should be noted these are not standard values. As expected, one of the more oxidant enzymes is the versatile peroxidase, which is able to catalyze the oxidation of Mn(II) to Mn (III) ( 0,=1.5 V). MPO has the highest two-electron redox potential, supporting the fact that only this enzyme is able to catalyze the oxidation of chloride to hypochlorite at neutral pH [72, 73], whereas eosinophil peroxidase performs better at acidic pH [74]. 

In some enzymes, the protein radical appears to participate in substrate oxidation. Evidence exists for the involvement of a surface tryptophan in the oxidation of veratryl alcohol by the ligninase from Phanerochaete chrysosporium [33]. Similarly, tryptophan radicals on the surface of the versatile peroxidases from Pleurotus eryngii and Bjerkandera adjusta [34—36], and a tyrosine in the LiP from Trametes cervina [33], are thought to be involved in substrate oxidation. 

As already mentioned, in some enzymes radicals generated on surface tryptophan and tyrosine radicals by electron transfer to the ferryl species are involved in abstraction of electrons from substrates [33-36, 40]. Mutation of Trpl71 on the surface of P. chrysosporium LiP to a phenylalanine or serine completely suppresses the veratryl alcohol oxidizing activity of the enzyme [40]. A similar depression in the oxidation of veratryl alcohol occurs on mutation of Trpl64 in the versatile peroxidase from P. eryngii [34, 35]. 

Pogni R, Baratto MC, Giansanti S et al (2005) Tryptophan-based radical in the catalytic mechanism of versatile peroxidase from Bjerkandera adusta. Biochemistry 44 44267 14274... 

Davila et al. [68] reported the transformation of the pesticides bromoxynil, dichlorophen, and pentachlorophenol by the versatile peroxidase from B. adusta. For the three transformed pesticides by versatile peroxidase, an oxidative dehalo-genation was observed, a very important process since the halogenated pesticides are considered more persistent and toxic than the organophosphorus pesticides, because of the carbon-halogen bond. Enzymatic transformation of dichlorophen compound... 

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