Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/194335
Type: Artigo de periódico
Title: Isolation And Partial Characterization Of An Extracellular Low-molecular Mass Component With High Phenoloxidase Activity From Thermoascus Aurantiacus.
Author: Machuca, A
Aoyama, H
Durán, N
Abstract: An extracellular low-molecular mass component (LMMC) with catalytic properties was isolated from liquid cultures containing wheat bran of ascomycete thermophilic Thermoascus aurantiacus. The partially purified LMMC showed very high activity with typical phenoloxidase substrates in the absence of hydrogen peroxide at acidic pH (2.8). However, in this pH range, the phenoloxidase (PO) activity was quickly lost. The LMMC showed a high optimum temperature (80 degrees C) and an elevated thermostability. The molecular mass of the component estimated by gel filtration chromatography was 530 Da. IR and 1H- and 13C-NMR spectra indicated the presence of hydroxamic acid moiety. Qualitative determination of metal ions by several techniques revealed the presence of mainly iron associated with this structure. Iron may be the responsible for the ability for catalyze oxidation reactions, such as o-dianisidine oxidation, by the LMMC. These results suggested the existence of a hydroxamate-type metal-binding component, most likely hydroxamate siderophore. In addition, the chrome azurol S (CAS) universal assay for noncomplexed siderophores detection revealed the production of these compounds by T.aurantiacus in solid and liquid media.
Subject: Ascomycota
Catalysis
Chromatography, Gel
Dianisidine
Dietary Fiber
Enzyme Stability
Hydrogen-ion Concentration
Hydroxamic Acids
Hydroxybenzoates
Iron
Kinetics
Molecular Weight
Monophenol Monooxygenase
Oxidants
Siderophores
Spectrum Analysis
Temperature
Rights: fechado
Identifier DOI: 10.1006/bbrc.1998.9927
Address: http://www.ncbi.nlm.nih.gov/pubmed/10066416
Date Issue: 1999
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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