An estimate of the kinetics of calcium binding and dissociation of the sarcoplasmic reticulum transport ATPase
| Autor: | Bernhard Rauch, Wilhelm Hasselbach, Dorothee von Chak |
|---|---|
| Jazyk: | angličtina |
| Předmět: |
ATPase
Inorganic chemistry Biophysics Biological Transport Active chemistry.chemical_element Calcium-Transporting ATPases Calcium Biochemistry Dissociation (chemistry) chemistry.chemical_compound Structural Biology Genetics Animals Phosphorylation Egtazic Acid Molecular Biology Cell-Free System biology Cell Biology Phosphoproteins Phosphate Rate-determining step Calcium ATPase Kinetics Sarcoplasmic Reticulum EGTA chemistry Phosphoprotein biology.protein Rabbits Carrier Proteins |
| Zdroj: | FEBS Letters |
| ISSN: | 0014-5793 |
| DOI: | 10.1016/0014-5793(78)80806-0 |
| Popis: | Maximal phosphorylation by ATP takes place only when the high affmity calcium binding sites of the protein are saturated. Conversely, phosphorylation by inorganic phosphate is achieved only when these binding sites are depleted of calcium ions. A recent kinetic analysis of the incorporation of inorganic phosphate into the transport protein led to the conclusion that either calcium removal itself or a subsequent reaction step in the formation of the phosphate accepting protein conformation might be the rate determining step [5]. A decision between these alternatives could be made if it were possible to measure the dissociation rate of the calcium-protein complex. Since there is no way to determine the dissociation of the complex directly, an indirect procedure will be applied. The decay of the calcium-protein complex is monitored by determining the amount of phosphoprotein which is formed when a saturating concentration of ATP is added to the protein after it has reacted for different short periods with EGTA. ATP will transfer its terminal phosphate only to those transport molecules still combined with calcium ions. This method for monitoring the dissociation of the calcium complex would fail if the dissociation reaction would proceed rapidly leading to a calcium-free but still phosphate- * |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|