| ID | 105 |
|---|---|
| Name | glutaminase |
| Synonyms | GA; Phosphate activated glutaminase; glutaminase; GLS; GLS 2; GLS2; Glutaminase I; L glutamine amidohydrolase… |
| ID | 1341 |
|---|---|
| Name | rotenone |
| CAS |
| PubMed | Abstract | RScore(About this table) |
|---|---|---|
| 5530189 | Kovacevic Z, McGivan JD, Chappell JB: Conditions for activity of glutaminase in kidney mitochondria. . Biochem J. 1970 Jun;118(2):265-74. 1. Rat kidney mitochondria oxidize very slowly. Addition of stimulates this respiration two- to three-fold. Addition of also stimulates respiration in the presence of 2. By measuring mitochondrial swelling in iso-osmotic solutions of or of ammonium it was shown that penetrates the mitochondrial membrane rapidly whereas ammonium penetrates very slowly. 3. Experiments in which reduction of NAD (P)(+) was measured in preparations of intact and broken mitochondria indicated that dehydrogenase shows the phenomenon of ;latency'. On the addition of rapid reduction of nucleotides in intact mitochondria was obtained. 4. During the action of glutaminase there is an accumulation of inside the mitochondria. 5. When the mitochondria were suspended in a medium containing P (i) and rotenone the rate of production of was stimulated by the addition of a substrate, e.g. Addition of an uncoupler or antimycin A abolished this stimulation. 6. The effects of and uncoupler were especially pronounced in the presence of which is an inhibitor of glutaminase activity by competition with P (i). 7. Determination of the enzyme activity in media at different pH values showed that the optimum pH for glutaminase activity in the preparation of broken mitochondria was 8, whereas for intact mitochondria it was dependent on the energy state. In the presence of as an energy source it was pH 8.5, but in the presence of uncoupler or antimycin A it was 9. This displacement of the pH optimum to a higher value was especially pronounced in the presence of both and uncoupler. 8. If nigericin was present in potassium chloride medium the pH optimum for enzyme activity in intact non-respiring mitochondria was nearly the same as in the preparation of broken mitochondria; however, its presence in K (+)-free medium displaced the pH optimum for glutaminase activity to a very high value. 9. It is postulated that because of low permeability of the kidney mitochondrial membrane to the latter accumulates inside the mitochondria, and that this leads to the inhibition of the enzyme by competition with P (i) and also by lowering the pH of the intramitochondrial space. With as substrate for respiration there is an outward translocation of H (+) ions, which together with accumulation of P (i) increases glutaminase activity. Translocation of K (+) ions inward increases the enzyme activity, perhaps by increasing the pH of the internal spaces and causing an accumulation of P (i). 10. The importance of the location of the enzyme in the mitochondria in relation to its biological function and conditions for activity is discussed. |
6(0,0,0,6) |