l-Aspartate Oxidase from Escherichia coli. II. Interaction with C4 Dicarboxylic Acids and Identification of a Novel l-Aspartate:Fumarate Oxidoreductase Activity
| Autor: | Severino Ronchi, Armando Negri, Gabriella Tedeschi, Ludovica Faotto, Fabrizio Ceciliani, Michele Mortarino, Tatjana Simonic |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
endocrine system diseases
Flavoprotein medicine.disease_cause Biochemistry Substrate Specificity Electron Transport chemistry.chemical_compound Biosynthesis Oxidoreductase Escherichia coli medicine Sulfites Dicarboxylic Acids Cloning Molecular L-aspartate oxidase chemistry.chemical_classification Oxidase test biology Escherichia coli Proteins nutritional and metabolic diseases Active site Electron acceptor Recombinant Proteins Kinetics chemistry Spectrophotometry biology.protein Amino Acid Oxidoreductases Oxidation-Reduction Mathematics hormones hormone substitutes and hormone antagonists |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1432-1033 0014-2956 |
| DOI: | 10.1111/j.1432-1033.1996.0427u.x |
| Popis: | L-Aspartate oxidase is a monomeric flavoprotein that catalyzes the first step in the de novo biosynthetic pathway for pyridine nucleotide formation under both aerobic and anaerobic conditions. In spite of the physiological importance of this biosynthesis in particular in facultative aerobic organisms, such as Escherichia coli, little is known about the electron acceptor of reduced L-aspartate oxidase in the absence of oxygen. In this report, evidence is presented which suggests that in vitro fumarate can play such a role. L-Aspartate oxidase binds succinate and fumarate with Kd values of 0.24 mM and 0.22 mM, respectively. A competitive behaviour was observed for these two dicarboxylic acids towards iminoaspartate and sulfite ions. Photoreduction experiments suggest that fumarate and succinate bind at or close to the active site of the molecule. A new fumarate reductase activity of L-aspartate oxidase is reported using benzylviologen or L-aspartate as reductants and fumarate as oxidant. Steady-state kinetics for the oxidase and the fumarate reductase activity of L-aspartate oxidase were obtained using either fumarate or oxygen as electron acceptor and L-aspartate as electron donor. Finally, succinate was identified as the product of the L-aspartate:fumarate oxidoreductase activity using radiolabeled fumarate under anaerobic conditions. The results suggest that fumarate can be a valuable alternative to oxygen as a substrate for L-aspartate oxidase. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|