| Autor: |
A, Raggi, M, Ranieri-Raggi |
| Rok vydání: |
1979 |
| Předmět: |
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| Zdroj: |
Biochimica et biophysica acta. 566(2) |
| ISSN: |
0006-3002 |
| Popis: |
1. Rat skeletal muscle AMP deaminase (AMP aminohydrolase, EC 3.5.4.6) at optimal KCl concentrations shows a biphasic response to increasing levels of the allosteric inhibitor ATP. 2. Up to 10 micrometer, ATP appears to convert the enzyme to a form exhibiting sigmoidal kinetics while at higher concentrations its inhibitory effect is manifested by an alteration of AMP binding to AMP deaminase indicative of negative homotropic cooperativity at about 50% saturation. 3. AMP deaminase is inactivated by incubation with the periodate oxidation product of ATP. The (oxidized ATP)--AMP deaminase complex stabilized by NaBH4 reduction shows kinetic properties similar to those of the native enzyme in the presence of high ATP concentrations. 4. A plausible explanation of the observed cooperativity is that ATP induces different conformational state of AMP deaminase subunits, causing the substrate to follow a sequential mechanism of binding to enzyme. 5. Binding of the radioactive oxidized ATP shows that 3.2 mol of this reagent bind per mol AMP deaminase. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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