IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Mitochondrial ATP synthesis is not the reversal of ATP hydrolysis-driven H+ translocation
Autor/es:
LODEYRO, A. F; CASTELLI, M.V; ROVERI, O. A.
Lugar:
Villa Carlos Paz- Córdoba- Argentina
Reunión:
Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular
Resumen:
<!-- /* Font Definitions */ @font-face {font-family:"MS Mincho"; panose-1:2 2 6 9 4 2 5 8 3 4; mso-font-alt:"MS 明朝"; mso-font-charset:128; mso-generic-font-family:modern; mso-font-pitch:fixed; mso-font-signature:-1610612033 1757936891 16 0 131231 0;} @font-face {font-family:"\@MS Mincho"; panose-1:2 2 6 9 4 2 5 8 3 4; mso-font-charset:128; mso-generic-font-family:modern; mso-font-pitch:fixed; mso-font-signature:-1610612033 1757936891 16 0 131231 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"MS Mincho"; mso-ansi-language:EN-GB;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Sulfate is a partial inhibitor at low and a non-essential activator at high [ATP] of the ATPase activity of F1. Therefore, a catalytically-competent ternary F1•ATP•sulfate complex can be formed. In addition, the ANS fluorescence enhancement driven by ATP hydrolysis in submitochondrial particles is also stimulated by sulfate, clearly showing that the ATP hydrolysis in its presence is coupled to H+ translocation. However, sulfate is a strong linear inhibitor of the mitochondrial ATP synthesis. The inhibition was competitive (Ki = 0.46 mM) with respect to Pi and mixed (Ki = 0.60 and Ki prima = 5.6 mM) towards ADP. Since it is likely that sulfate exerts its effects by binding at the Pi binding subdomain of the catalytic site, we suggest that the catalytic site involved in the H+ translocation driven by ATP hydrolysis has a more open conformation than the half-closed one (BHC), which is an intermediate in ATP synthesis. Accordingly, ATP hydrolysis is not necessarily the exact reversal of ATP synthesis.