Spectral and catalytic properties of aryl-alcohol oxidase, a fungal flavoenzyme acting on polyunsaturated alcohols
AUTOR(ES)
Ferreira, Patricia
FONTE
Portland Press Ltd.
RESUMO
Spectral and catalytic properties of the flavoenzyme AAO (aryl-alcohol oxidase) from Pleurotus eryngii were investigated using recombinant enzyme. Unlike most flavoprotein oxidases, AAO does not thermodynamically stabilize a flavin semiquinone radical and forms no sulphite adduct. AAO catalyses the oxidative dehydrogenation of a wide range of unsaturated primary alcohols with hydrogen peroxide production. This differentiates the enzyme from VAO (vanillyl-alcohol oxidase), which is specific for phenolic compounds. Moreover, AAO is optimally active in the pH range of 5–6, whereas VAO has an optimum at pH 10. Kinetic studies showed that AAO is most active with p-anisyl alcohol and 2,4-hexadien-1-ol. AAO converts m- and p-chlorinated benzyl alcohols at a similar rate as it does benzyl alcohol, but introduction of a p-methoxy substituent in benzyl alcohol increases the reaction rate approx. 5-fold. AAO also exhibits low activity on aromatic aldehydes. 19F NMR analysis showed that fluorinated benzaldehydes are converted into the corresponding benzoic acids. Inhibition studies revealed that the AAO active site can bind a wide range of aromatic ligands, chavicol (4-allylphenol) and p-anisic (4-methoxybenzoic) acid being the best competitive inhibitors. Uncompetitive inhibition was observed with 4-methoxybenzylamine. The properties described above render AAO a unique oxidase. The possible mechanism of AAO binding and oxidation of substrates is discussed in the light of the results of the inhibition and kinetic studies.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1180723Documentos Relacionados
- Anisaldehyde production and aryl-alcohol oxidase and dehydrogenase activities in ligninolytic fungi of the genus Pleurotus.
- Electron and Fluorescence Microscopy of Extracellular Glucan and Aryl-Alcohol Oxidase during Wheat-Straw Degradation by Pleurotus eryngii
- Aryl-alcohol Oxidase Involved in Lignin Degradation: A MECHANISTIC STUDY BASED ON STEADY AND PRE-STEADY STATE KINETICS AND PRIMARY AND SOLVENT ISOTOPE EFFECTS WITH TWO ALCOHOL SUBSTRATES*
- Direct Enzymatic Assay for Alcohol Oxidase, Alcohol Dehydrogenase, and Formaldehyde Dehydrogenase in Colonies of Hansenula polymorpha
- Catechol Oxidase, Phosphatase-Like Activity, DNA/BSA Binding Studies of RuII Complexes of S-Allyldithiocarbazate: Synthesis and Spectral Studies