The transported cations impose differences in the thermostability of the gastric H,K-ATPase. A kinetic analysis.

Autor: Valsecchi WM; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas 'Prof. Alejandro C. Paladini' (IQUIFIB), Buenos Aires, Argentina., Faraj SE; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas 'Prof. Alejandro C. Paladini' (IQUIFIB), Buenos Aires, Argentina., Cerf NT; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas 'Prof. Alejandro C. Paladini' (IQUIFIB), Buenos Aires, Argentina., Fedosova NU; Department of Biomedicine, Aarhus University, Aarhus, Denmark., Montes MR; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas 'Prof. Alejandro C. Paladini' (IQUIFIB), Buenos Aires, Argentina. Electronic address: mmontes@qb.ffyb.uba.ar.
Jazyk: angličtina
Zdroj: Biochimica et biophysica acta. Biomembranes [Biochim Biophys Acta Biomembr] 2022 Nov 01; Vol. 1864 (11), pp. 184006. Date of Electronic Publication: 2022 Jul 19.
DOI: 10.1016/j.bbamem.2022.184006
Abstrakt: This work analyses the thermostability of a membrane protein, the gastric H,K-ATPase, by means of a detailed kinetic characterization of its inactivation process, which showed to exhibit first-order kinetics. We observed parallel time courses for the decrease of ATPase activity, the decrease of the autophosphorylation capacity and the loss of tertiary structure at 49 °C. Higher temperatures were required to induce a significant change in secondary structure. The correspondence between the kinetics of Trp fluorescence measured at 49 °C and the decrease of the residual activity after heating at that temperature, proves the irreversibility of the inactivation process. Inactivation proceeds at different rates in E1 or E2 conformations. The K + -induced E2 state exhibits a lower inactivation rate; the specific effect is exerted with a K 0.5 similar to that found at 25 °C, providing a further inkling that K + occlusion by the H,K-ATPase is not really favoured. Increasing [H + ] from pH 8 to pH 7, which possibly shifts the protein to E1, produces a subtle destabilizing effect on the H,K-ATPase. We performed a prediction of potential intramolecular interactions and found that the differential stability between E1 and E2 may be mainly explained by the higher number of hydrophobic interactions in the α- and β-subunits of E2 conformation.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2022 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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