IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Exploring the effects of ligands on thermal stability of A. fulgidus Cu+-ATPase
Autor/es:
NOELIA I. BURGARDT; DIEGO I. CATTONI; JOSÉ M ARGUELLO; F. LUIS GONZÁLEZ-FLECHA
Lugar:
Salta
Reunión:
Congreso; 3rd LatinAmerican Protein Society Meeting; 2010
Institución organizadora:
Sociedad Argentina de Biofisica
Resumen:
Folding and stability are determinant elements of protein biological functions. Despite membrane proteins are a large fraction of proteomes1, little is known about membrane protein stability. In this work the thermophilic Cu+ ATPase from Archaeoglobus fulgidus (CopA) was used as a model to study stabilizing mechanisms in membrane proteins. CopA is a P type ATPases witch transport heavy metals (Cu+, Ag+, etc.) across biological membranes2. We have previously characterised the kinetic thermal stability of CopA in the absence of substrates. The result obtained shows an irreversible exponential decrease of enzyme activity which suggests a two state process involving only fully active and inactive molecules3. To study the effects of ligand on CopA stability we performed inactivation assays at different Ag+/Cys or ATP/Mg+2 concentrations. The stability of the enzyme was evaluated before activity measurement as well as during the reaction cycle. CopA inactivation was not significantly different when the enzyme was incubated in the presence of Ag+/Cys, but in the presence of ATP/Mg2+ the inactivation rate was lower. These results suggest that ATP protect the protein for thermal inactivation; meanwhile the metal ion does not. In the other hand, when CopA was incubated in the presence of all its biological ligands the inactivation was slower than in the previous assays, suggesting that CopA stability is enhanced when the enzyme is performing the reaction cycle.