title: Electrogenic steps of the SR Ca-ATPase enzymatic cycle and the effect of curcumin.
abstract: Sarcoplasmic reticulum (SR) vesicles were adsorbed on an octadecanethiol/phosphatidylcholine mixed bilayer anchored to a gold electrode, and the Ca-ATPase contained in the vesicles was activated by ATP concentration jumps in the presence of calcium ions. The resulting capacitive current transients are compared with those calculated on the basis of the enzymatic cycle of the calcium pump. This comparison provides information on the kinetics of the E(2)-E(1) conformational change and on its pH dependence. The alteration in the current transients following ATP concentration jumps in the presence of curcumin is examined. In particular, curcumin decreases the rate of slippage of the Ca-ATPase, and at concentrations above 10 microM reduces calcium transport by this pump.
authors.affiliation: Department of Chemistry, University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Bartolommei
authors.forename: Francesco
authors.initials: F
authors.lastname: Tadini-Buoninsegni
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Moncelli
authors.forename: Rolando
authors.initials: R
authors.lastname: Guidelli
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D003474:Curcumin / Q000494:pharmacology*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*
chemical_list: D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; D003474:Curcumin