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; JOSE M ARGUELLO; F LUIS GONZALEZ FLECHA
Lugar:
Salta
Reunión:
Congreso; XXXIX Reunion de la Sociedad Argentina de Biofisica; 2010
Institución organizadora:
Sociedad Argentina de Biofisica
Resumen:
148
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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.