Peroxidase catalytic cycle of MCM-41-entrapped microperoxidase-11 as a mechanism for phenol oxidation
| Autor: | Juliana C. Araujo, Francisco L. Castro, Gabriel L. C. Nunes, Antonio S. Araujo, Glauber José Turolla Fernandes, Fernanda M. Prado, Mário José Politi, Fabiane J. Trindade, Otaciro R. Nascimento, Valter J. Fernandes, Jean G. dos Santos, Paolo Di Mascio, Iseli L. Nantes, Tatiana Prieto, Sergio Brochsztain |
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| Rok vydání: | 2008 |
| Předmět: |
Hemeprotein
Reducing agent Inorganic chemistry Biomedical Engineering Bioengineering Catalysis Absorption chemistry.chemical_compound Materials Testing Nanotechnology General Materials Science Particle Size Hydrogen peroxide Heme biology Phenol General Chemistry Condensed Matter Physics Enzymes Immobilized Silicon Dioxide Nanostructures chemistry Catalytic cycle Peroxidases Catalase biology.protein Crystallization Oxidation-Reduction Peroxidase Nuclear chemistry |
| Zdroj: | Journal of nanoscience and nanotechnology. 7(10) |
| ISSN: | 1533-4880 |
| Popis: | The encapsulation of microperoxidases (MPs) into molecular sieves with controlled pore size, such as the mesoporous silica MCM-41, represents a nanotechnology strategy to control the catalytic properties of MPs and mimic the enzymatic activity of hemoproteins. In this work, the ferric microperoxidase-11 (MP-11), obtained from trypsin-catalyzed hydrolysis of horse-heart cytochrome c, was entrapped in MCM-41, thus resulting in a catalyst (Fe(III)MP11MCM41) with catalase and monooxygenase properties. The entrapment of MP-11 inside MCM-41 was confirmed by elemental analysis and UV-visible spectrum, with a red shift in the Soret band indicating that the heme group was in a hydrophobic microenvironment. Similarly to catalase, the catalyst Fe(III)MP11MCM41 exhibited specificity for hydrogen peroxide to be converted to a high-valence oxidized intermediate, Compound II. Also mimicking catalase, the cleavage of hydrogen peroxide by MP11MCM41 resulted in O2 production detected by a Clark electrode. Phenol was able to act as reducing agent of MP11MCM41 Compound II leading to the completion of a peroxidase cycle, as confirmed by UV-visible spectrometry and EPR measurements. The analysis of the reaction products by high performance liquid chromatogram coupled to tandem mass spectrometry (HPLC/MS) revealed 2,4-dihydroxyphenol as the product of phenol oxidation by MP11MCM41. Therefore, in addition to catalase activity, the catalyst MP11MCM41 also displayed monooxygenase properties, which was possible because the MP-11 heme iron promotes homolytic cleavage of the hydrogen peroxide generating hydroxyl radicals. With such characteristics, MCM-41-entrapped MP-11 is a promising catalyst for nanobiotechnological devices. |
| Databáze: | OpenAIRE |
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