A kinetic comparison between E2P and the E2P-like state induced by a beryllium fluoride complex in the Na,K-ATPase. Interactions with Rb+
| Autor: | Rolando C. Rossi, Monica Raquel Montes, Santiago Enrique Faraj, Mercedes Centeno |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Conformational change
Time Factors Protein Conformation Swine ENZYME MECHANISM ATPase NA K-ATPASE Biophysics RB+ OCCLUSION AND DEOCCLUSION Biochemistry Models Biological Fluorescence Phosphates PHOSPHORYLATED STATES purl.org/becyt/ford/1 [https] Ciencias Biológicas 03 medical and health sciences chemistry.chemical_compound Fluorides Animals Enzyme kinetics Na+/K+-ATPase purl.org/becyt/ford/1.6 [https] Conformational isomerism 030304 developmental biology 0303 health sciences biology Chemistry 030302 biochemistry & molecular biology Imidazoles CONFORMATIONAL CHANGE Cell Biology Membrane transport Bioquímica y Biología Molecular Rubidium Biofísica Beryllium fluoride Crystallography Kinetics biology.protein MEMBRANE TRANSPORT ENZYME KINETICS LIGAND BINDING KINETICS Beryllium Sodium-Potassium-Exchanging ATPase Cation transport CIENCIAS NATURALES Y EXACTAS |
| Zdroj: | CONICET Digital (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas instacron:CONICET |
| Popis: | Metal-fluoride complexes have been used to induce E2P-like states with the aim of studying the events that occur during E2P hydrolysis in P-type ATPases. In the present work, we compared the E2P-like state induced by a beryllium fluoride complex (BeFx) with the actual E2P state formed through backdoor phosphorylation of the Na,K-ATPase. Formation of E2P and E2P-like states were investigated employing the styryl dye RH421. We found that BeFx is the only fluorinated phosphate analog that, like Pi, increases the RH421 fluorescence. The observed rate constant, kobs, for the formation of E2P decreases with [Pi] whereas that of E2BeFx increases with [BeFx]. This might wrongly be taken as evidence of a mechanism where the binding of BeFx induces a conformational transition. Here, we rather propose that, like for Pi, binding of BeFx follows a conformational-selection mechanism, i.e. it binds to the E2 conformer forming a complex that is much more stable than E2P, as seen from its impaired capacity to return to E1 upon addition of Na+. Although E2P and E2BeFx are able to form states with 2 occluded Rb+, both enzyme complexes differ in that the affinity for the binding and occlusion of the second Rb+ is much lower in E2BeFx than in E2P. The higher rates of Rb+ occlusion and deocclusion observed for E2BeFx, as compared to those observed for other E2P-like transition and product states suggest a more open access to the cation transport sites, supporting the idea that E2BeFx mimics the E2P ground state. Fil: Faraj, Santiago Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Centeno, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Rossi, Rolando Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Montes, Monica Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina |
| Databáze: | OpenAIRE |
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