INVESTIGADORES
MONTES Monica Raquel
congresos y reuniones científicas
Título:
-Comparison of Rb+ release and conformational change in the Na+/K+-ATPase
Autor/es:
MONTES MÓNICA; RODOLFO GONZÁLEZLEBRERO; PATRICIO GARRAHAN; ROLANDO ROSSI
Lugar:
Buenos Aires
Reunión:
Congreso; XIV International Biophysics Congress Annual Meeting; 2002
Institución organizadora:
IUPAB
Resumen:
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Abstract Number: 504
A PARALLEL STUDY OF K+ OCCLUSION AND
CONFORMATIONAL CHANGES IN THE Na+/K+-ATPase.
Montes M.R., González-Lebrero r.M., Garrahan P.J., Rossi R.C.
IQUIFIB. Facultad de Farmacia y
Bioquímica (Universidad Nacional de Buenos Aires) Junín 956 (1113) Buenos
Aires-Argentina. mmontes@qb.ffyb.uba.ar
The
transport cycle of the Na+/K+-ATPase
occurs through a set of kinetically distinguishable conformational states
of the enzyme, one with high affinity for Na+, E1, and the other with high affinity for K+, E2. The aim of this work is a
comparative characterization of the kinetics of the E1 Ç E2 conformational transition,
measuring eosin-fluorescence (a probe of the E1 form) and K+ occlusion (assumed to occur
in the E2 form of the
enzyme), in parallel experiments. Instead of K+, we used the labeled
congener [86Rb]Rb+ and measured occluded Rb+
(Rbocc) as described by Rossi et al. (Anal. Biochem., 270:276-285). We first evaluated the effects of eosin on Rbocc
both in equilibrium and transient experiments. Results show that eosin binds
both to the free enzyme and to enzyme containing occluded Rb+, and
that the rate of release of occluded Rb+ from Rbocc was
considerably increased by eosin while the initial slope of formation of Rbocc
was decreased by the fluorescent probe.
Stopped-flow
experiments measuring the time course of eosin fluorescence change showed
similar parameters as those obtained measuring the time course of formation of
Rbocc.
With
grants from ANPCyT, UBA and CONICET, Argentina.
