The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+
We used the direct route of occlusion to study the equilibrium between free and occluded Rb+ in the Na+/K+-ATPase, in media with different concentrations of ATP, Mg2+, or Na+. An empirical equation, with the restrictions imposed by the stoichiometry of ligand binding was fitted to the data. This all...
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todo:paper_00219258_v277_n8_p5922_GonzalezLebrero2023-10-03T14:23:02Z The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+ González-Lebrero, R.M. Kaufman, S.B. Garrahan, P.J. Rossi, R.C. Magnesium printing plates Physiology Positive ions Potassium Rubidium Sodium Stoichiometry Occlusion capacity Enzymes adenosine triphosphatase (potassium sodium) adenosine triphosphate magnesium ion nucleotide rubidium ion sodium ion article enzyme analysis equilibrium constant ligand binding priority journal stoichiometry Adenosine Triphosphate Animals Kidney Kinetics Magnesium Models, Theoretical Na(+)-K(+)-Exchanging ATPase Rubidium Sodium Swine We used the direct route of occlusion to study the equilibrium between free and occluded Rb+ in the Na+/K+-ATPase, in media with different concentrations of ATP, Mg2+, or Na+. An empirical equation, with the restrictions imposed by the stoichiometry of ligand binding was fitted to the data. This allowed us to identify which states of the enzyme were present in each condition and to work out the schemes and equations that describe the equilibria between the ATPase, Rb+, and ATP, Mg2+, or Na+. These equations were fitted to the corresponding experimental data to find out the values of the equilibrium constants of the reactions connecting the different enzyme states. The three ligands decreased the apparent affinity for Rb+ occlusion without affecting the occlusion capacity. With [ATP] tending to infinity, enzyme species with one or two occluded Rb+ seem to be present and full occlusion seems to occur in enzymes saturated with the nucleotide. In contrast, when either [Mg2+] or [Na+] tended to infinity no occlusion was detectable. Both Mg2+ and Na+ are displaced by Rb+ through a process that seems to need the binding and occlusion of two Rb+, which suggests that in these conditions Rb+ occlusion regains the stoichiometry of the physiological operation of the Na+ pump. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00219258_v277_n8_p5922_GonzalezLebrero |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Magnesium printing plates Physiology Positive ions Potassium Rubidium Sodium Stoichiometry Occlusion capacity Enzymes adenosine triphosphatase (potassium sodium) adenosine triphosphate magnesium ion nucleotide rubidium ion sodium ion article enzyme analysis equilibrium constant ligand binding priority journal stoichiometry Adenosine Triphosphate Animals Kidney Kinetics Magnesium Models, Theoretical Na(+)-K(+)-Exchanging ATPase Rubidium Sodium Swine |
| spellingShingle |
Magnesium printing plates Physiology Positive ions Potassium Rubidium Sodium Stoichiometry Occlusion capacity Enzymes adenosine triphosphatase (potassium sodium) adenosine triphosphate magnesium ion nucleotide rubidium ion sodium ion article enzyme analysis equilibrium constant ligand binding priority journal stoichiometry Adenosine Triphosphate Animals Kidney Kinetics Magnesium Models, Theoretical Na(+)-K(+)-Exchanging ATPase Rubidium Sodium Swine González-Lebrero, R.M. Kaufman, S.B. Garrahan, P.J. Rossi, R.C. The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+ |
| topic_facet |
Magnesium printing plates Physiology Positive ions Potassium Rubidium Sodium Stoichiometry Occlusion capacity Enzymes adenosine triphosphatase (potassium sodium) adenosine triphosphate magnesium ion nucleotide rubidium ion sodium ion article enzyme analysis equilibrium constant ligand binding priority journal stoichiometry Adenosine Triphosphate Animals Kidney Kinetics Magnesium Models, Theoretical Na(+)-K(+)-Exchanging ATPase Rubidium Sodium Swine |
| description |
We used the direct route of occlusion to study the equilibrium between free and occluded Rb+ in the Na+/K+-ATPase, in media with different concentrations of ATP, Mg2+, or Na+. An empirical equation, with the restrictions imposed by the stoichiometry of ligand binding was fitted to the data. This allowed us to identify which states of the enzyme were present in each condition and to work out the schemes and equations that describe the equilibria between the ATPase, Rb+, and ATP, Mg2+, or Na+. These equations were fitted to the corresponding experimental data to find out the values of the equilibrium constants of the reactions connecting the different enzyme states. The three ligands decreased the apparent affinity for Rb+ occlusion without affecting the occlusion capacity. With [ATP] tending to infinity, enzyme species with one or two occluded Rb+ seem to be present and full occlusion seems to occur in enzymes saturated with the nucleotide. In contrast, when either [Mg2+] or [Na+] tended to infinity no occlusion was detectable. Both Mg2+ and Na+ are displaced by Rb+ through a process that seems to need the binding and occlusion of two Rb+, which suggests that in these conditions Rb+ occlusion regains the stoichiometry of the physiological operation of the Na+ pump. |
| format |
JOUR |
| author |
González-Lebrero, R.M. Kaufman, S.B. Garrahan, P.J. Rossi, R.C. |
| author_facet |
González-Lebrero, R.M. Kaufman, S.B. Garrahan, P.J. Rossi, R.C. |
| author_sort |
González-Lebrero, R.M. |
| title |
The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+ |
| title_short |
The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+ |
| title_full |
The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+ |
| title_fullStr |
The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+ |
| title_full_unstemmed |
The occlusion of Rb+ in the Na+/K+-ATPase. II. The effects of Rb+, Na+, Mg2+, or ATP on the equilibrium between free and occluded Rb+ |
| title_sort |
occlusion of rb+ in the na+/k+-atpase. ii. the effects of rb+, na+, mg2+, or atp on the equilibrium between free and occluded rb+ |
| url |
http://hdl.handle.net/20.500.12110/paper_00219258_v277_n8_p5922_GonzalezLebrero |
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