N-Acetyl-6-hydroxytryptophan oxidase, a developmentally controlled phenol oxidase from Aspergillus nidulans
| Autor: | A J Clutterbuck, C E Birse |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
chemistry.chemical_classification
Oxidase test Hot Temperature biology Monophenol Monooxygenase Stereochemistry Molecular Sequence Data Substrate (chemistry) biology.organism_classification Binding Competitive Microbiology Aspergillus nidulans Substrate Specificity chemistry.chemical_compound Enzyme Phenols chemistry Enzyme Stability Amino Acid Sequence Thermolabile Tyrosine Copper Phenylhydrazine |
| Zdroj: | Journal of General Microbiology. 136:1725-1730 |
| ISSN: | 0022-1287 |
| Popis: | Summary: We have purified a specific phenol oxidase which is produced during conidiophore development in the fungus Aspergillus nidulans. Two active forms (A and B) have molecular masses of 50 and 48 kDa respectively; they have identical N-termini (24 residues). We have analysed the metal ion content of the B form; it is unusual in consisting of one zinc and two copper atoms per molecule. A temperature-sensitive mutant (ivoB192) produces a thermolabile enzyme, implying that ivoB is the structural locus. The natural substrate of the enzyme is N-acetyl-6-hydroxytryptophan, but it can be assayed colorimetrically or polarographically using hydroquinone monomethyl ether (HME) as substrate. It will also oxidize p-cresol, but not tyrosine, 3,4-dihydroxyphenylalanine or o-methoxyphenol. Colour development with HME substrate is strongly enhanced by high ammonium ion concentrations. Activity against HME is inhibited by 2,3-dihydroxynaphthalene, phenylhydrazine, diethyl dithiocarbamate and 8-hydroxyquinolene. |
| Databáze: | OpenAIRE |
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