Mechanism of regulation of the malic enzyme from Fusarium
| Autor: | M. W. Zink |
|---|---|
| Rok vydání: | 1974 |
| Předmět: |
Fusarium
Oxaloacetates Stereochemistry Immunology Malates Malic enzyme Decarboxylation Gluconates Applied Microbiology and Biotechnology Microbiology Phosphates chemistry.chemical_compound Malate Dehydrogenase Fusarium oxysporum Genetics Sulfhydryl Compounds Molecular Biology Oxidative decarboxylation Mercaptoethanol Aspartic Acid Cell-Free System biology Fructosephosphates food and beverages Succinates General Medicine Hydrogen-Ion Concentration biology.organism_classification chemistry Biochemistry Glycerophosphates Malic acid NADP |
| Zdroj: | Canadian Journal of Microbiology. 20:443-454 |
| ISSN: | 1480-3275 0008-4166 |
| DOI: | 10.1139/m74-069 |
| Popis: | The NADP-specific malic enzyme which catalyzes the oxidative decarboxylation of malic acid has been partially purified from extracts of Fusarium oxysporum and some of its kinetic parameters studied. Reciprocal velocity plots with malate as variable substrate are nonlinear except at high NADP concentration, while with NADP as variable substrate the reciprocal plots are linear. Substrate activation by malic acid describes a biphasic character in reciprocal plots. Kinetic studies indicate that there are two binding sites for malic acid. At saturating levels of NADP, two Km components for malic acid, designated as [Formula: see text] and [Formula: see text] are evident. The separation of the two components may have been accomplished; [Formula: see text] component by mercaptosuccinic acid and [Formula: see text] component by either low pH or by phosphate. Inhibition of the purified malic enzyme is nontotal with fructose 1,6-diphosphate, 6-phosphogluconic acid, and 3-phos-phoglyceric acid. The kinetic relationship between fructose 1,6-diphosphate or 6-phospho-gluconate and malic acid is competitive with respect to the [Formula: see text] component and noncompetitive with [Formula: see text] component. Inhibition by 3-phosphoglyceric acid and oxaloacetate with respect to both components is noncompetitive and competitive, respectively. The significance of negative cooperativity and the effect of the above-mentioned inhibitors is discussed. |
| Databáze: | OpenAIRE |
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