Martinez-Azorin F.Cyclopiazonic
acid reduces the coupling factor of the Ca2+-ATPase acting on
Ca2+ binding.
FEBS Lett. 2004 Oct 8;576(1-2):73-6.
Departamento de Bioquímica (B-19), Facultad de Medicina
(CSIC-UAM), Universidad Autónoma de Madrid, Arturo Duperier 4,
E-28029 Madrid, Spain. fazorin@iib.uam.es
The mycotoxin cyclopiazonic acid (CPA) is a potent inhibitor of
the sarcoplasmic reticulum Ca2+-ATPase. The compound decreases
the affinity of the Ca2+-ATPase for Ca2+ and reduces the maximum
specific activity of the enzyme. Furthermore, CPA abolishes the
cooperativity of Ca2+ transport, showing a Ca2+/ATP ratio
approximately 1 at any extent of Ca2+ saturation. There is also
an effect on the Ca2+-binding mechanism, where the addition of
CPA results in binding of only half-maximal amount of Ca2+
observed in its absence. The experimental data suggest that in
the presence of CPA, only a single Ca2+ ion binds to the
Ca2+-ATPase. Copyright 2004 Federation of European Biochemical
Societies
PMID: 15474013
|
