INVESTIGADORES
GONZALEZ LEBRERO Rodolfo Martin
artículos
Título:
The interaction between the fluorescent probe eosin and the Na+/K+ ATPase studied through Rb+ occlusion
Autor/es:
MÓNICA R, MONTES; RODOLFO MARTIN GONZALEZ LEBRERO; PATRICIO J, GARRAHAN; ROLANDO CARLOS, ROSSI
Revista:
BIOCHEMISTRY
Editorial:
AMER CHEMICAL SOC
Referencias:
Año: 2004 vol. 43 p. 2062 - 2069
ISSN:
0006-2960
Resumen:
P { margin-bottom: 0.21cm; }
We report a study on the effect of the
fluorescent probe eosin on some of the reactions involved
in the
conformational transitions that lead to the occlusion of the
K+-congener Rb+ in the Na+/K+-
ATPase. Eosin decreases the
equilibrium levels of occluded Rb+, this effect being fully
attributable to a
decrease in the apparent affinity of the enzyme
for Rb+ since the capacity for occlusion remains independent
of
eosin concentration. The results can be quantitatively described by a
model that assumes that two
molecules of eosin are able to bind to
the Na+/K+-ATPase, both to the Rb+-free and to the Rb+-occluded
enzyme regardless of the degree of cation occlusion. Concerning the
effect on the affinity for Rb+ occlusion,
transient state
experiments show that eosin reduces the initial velocity of
occlusion, and that, like ATP,
it increases the velocity of
deocclusion of Rb+. Interactions between eosin and ATP on
Rb+-release
experiments seem to indicate that eosin binds to the
low-affinity site of ATP from which it exerts effects
that are
similar to those of the nucleotide.
