tailieunhanh - Báo cáo Y học: Inhibition of the SERCA Ca21 pumps by curcumin Curcumin putatively stabilizes the interaction between the nucleotide-binding and phosphorylation domains in the absence of ATP

School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK; 2Shifa College of Medicine, Islamabad, is a compound derived from the spice, tumeric. It is a potent inhibitor of the SERCA Ca2þ pumps (all isoforms), inhibiting Ca2þ-dependent ATPase activity with IC50 values of between 7 and 15 mM . It also inhibits ATPdependent Ca2þ-uptake in a variety of microsomal membranes, although for cerebellar and platelet microsomes, a stimulation in Ca2þ uptake is observed at low curcumin concentrations (,10 mM ) | Eur. J. Biochem. 268 6318-6327 2001 FEBS 2001 Inhibition of the SERCA Ca21 pumps by curcumin Curcumin putatively stabilizes the interaction between the nucleotide-binding and phosphorylation domains in the absence of ATP Jonathan G. Bilmen1 Shahla Zafar Khan1 Masood-ul-Hassan Javed2 and Francesco Michelangeli1 School of Biosciences University of Birmingham Edgbaston Birmingham UK 2Shifa College of Medicine Islamabad Pakistan. Curcumin is a compound derived from the spice tumeric. It is a potent inhibitor of the SERCA Ca2 pumps all isoforms inhibiting Ca2 -dependent ATPase activity with IC50 values of between 7 and 15 mM. It also inhibits ATP-dependent Ca2 -uptake in a variety of microsomal membranes although for cerebellar and platelet microsomes a stimulation in Ca2 uptake is observed at low curcumin concentrations 10 mM . For the skeletal muscle isoform of the Ca2 pump SERCA1 the inhibition of curcumin is noncompetitive with respect to Ca2 and competitive with respect to ATP at high curcumin concentrations 10-25 mM . This was confirmed by ATP binding studies that showed inhibition in the presence of curcumin ATP-dependent phosphorylation was also reduced. Experiments with fluorescein 50-isothiocyanate FITC -labelled ATPase also suggest that curcumin stabilizes the E1 conformational state. The fact that FITC labels the nucleotide binding site of the ATPase precluding ATP from binding and the fact that curcumin affects FITC fluorescence indicate that curcumin must be binding to another site within the ATPase that induces a conformational change to prevent ATP from binding. This observation is interpreted with the aid of recent structural information as curcumin stabilizing the interaction between the nucleotide-binding and phosphorylation domains precluding ATP binding. Keywords SERCA ATP binding curcumin phosphorylation fluorescence. Tumeric is extensively used as a spice in Asian cooking and as a colouring agent in both the food and cosmetic industries 1 . .