1. N-Demethylation of Methylene Blue by Lignin Peroxidase from Phanerochaete chrysosporium
- Author
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Elba P. S. Bon, Veronica de Sá Ferreira, S. H. Kling, J G da Silva Júnior, and Denise Bello Magalhães
- Subjects
Triphenylmethane ,biology ,Substrate (chemistry) ,Bioengineering ,Azure A ,General Medicine ,Lignin peroxidase ,biology.organism_classification ,Applied Microbiology and Biotechnology ,Biochemistry ,chemistry.chemical_compound ,chemistry ,Yield (chemistry) ,Phanerochaete ,Crystal violet ,Molecular Biology ,Methylene blue ,Biotechnology ,Nuclear chemistry - Abstract
Phanerochaete chrysosporium lignin peroxidase (LiP) can degrade synthetic dyes such as heterocyclic, azo, and triphenylmethane on its activation by H2O2. Analysis of the reaction products indicated that N-demethylation reactions are involved in the degradation of crystal violet and methylene blue (MB). We studied LiP oxidation of methylene blue and azure B (AB) in reaction mixtures containing different dye:H2O2 stoichiometric relations aiming at the selective formation of N-demethylated derivatives. High yields, about 70%, of the mono- and didemethylated derivatives, azure B and azure A, were obtained with the use of 1:1 and 1:2 MB:H2O2, respectively. Using azure B as substrate in reaction mixtures containing 1:1 AB:H2O2, a yield of 70% was also observed in azure A. Reaction mixtures containing 1:3 MB:H2O2 and 1:2 AB:H2O2, originated several oxidation products in similar proportions. These results indicated that the process of enzymatic degradation of methylene blue and azure B initiates via N(CH3)2 oxidation. According to the yields that were obtained for azure B and azure A, this enzymatic route can be used for the synthesis of these dyes since these data compare favorably to the chemical route that has a yield of 35%. The use of a dye:H2O2 relation of 1:10 resulted in a decoloration level of about 85%, showing the usefulness of this procedure for wastewater treatment. The reaction products were followed by spectrophotometric analysis within the wavelength of 500-700 nm. The product identifications were performed using a reverse-phase high-performance liquid chromatography (HPLC) C-18 column and thin-layer chromatography.
- Published
- 2000