The natural polyphenol, epigallocatechin-3- gallate, inhibits the Plasma Membrane Ca 2+ -ATPase in vitro and in vivo

RINALDI, D.E.; SAFFIOTI N, MANGIALAVORI, I., REY, O, ROSSI, R; FERREIRA-GOMES, M.; ROSSI, J.P

San Miguel de Tucumán

Congreso; 242. III Latin American Federation of Biophysical Societies (LAFeBS) IX IberoAmerican Congress of Biophysics XLV Reunion Anual SAB 2016; 2016

Sociedad Argentina de Biofísica

Tipo:PósterTópico:Proteins,Structure and FunctionMembrane Transporters andChannels The natural polyphenol,epigallocatechin-3-gallate, inhibits thePlasma Membrane Ca2+-ATPasein vitro and in vivoRinaldi, D.E.; SaffiotiN, Mangialavori, I., Rey, O, Rossi, R;Ferreira-Gomes, M.; Rossi, J.P.Instituto de Química y FisicoquímicaBiológicas. ?Prof. Dr. A.C. Paladini?. Departamento de Química Biológica,Facultad de Farmacia y Bioquímica,Universidad de Buenos Aires.derinaldiw@gmail.comEpigallocatechin 3-gallate (EGCG)is the major polyphenol component of green tea. This compound is believed to bethe main responsible for many of the health benefits associated with green tea.EGCG beneficial effects include antioxidant, anti-inflammatory and neuroprotectiveeffects. EGCG produces alterations in intracellular Ca2+ homeostasiswhich could be linked to the function of the Sarcoplasmic Reticulum Calcium Pump(SERCA). The maintenance of intracellular calcium levelsis fine-tuned by the PlasmaMembrane Ca2+-ATPase (PMCA). Therefore, we investigated the effect ofdifferent flavan-3-ols and went into detail about the EGCG effect on PMCA. We performed measurementsof the Ca2+-ATPaseactivity on PMCA purified from human red blood cells and of Ca2+ flux on HEK293Tcells that overexpress PMCA4. We evaluated PMCA ATPase activity in the presenceof catechin (C), epicatechin (EC) and epigallocatechin. C and EC showed noeffect up to 100 mM. However,EGCG showed a strong inhibition with a K0.5 of 0.032 ± 0.003mM. Under similarconditions, EGCg showed an increase of the phosphorylatedintermediate which was found to be ADP sensitive, suggesting that EGCG could stabilizethe E1P conformation on the reactioncycle of hydrolysis of ATP by PMCA. We performed docking assays of EGCGas ligand and PMCA structure models as the receptor. PMCA models were obtainedby homology modelling on SERCA crystallographic structures in differentconformations. Our results showed that ECGC binds mainly to the closedconformations of the enzyme. Particularly the E1P conformation forms lowest free binding energy complexes withthe ligand establishing hydrogen bonds with both the P and N domains of thepump.On the other hand, Ca2+efluxin HEK293 cells are inhibited by EGCG invivo showing its physiological relevance on PMCA activity.With grants of CONICET, ANPCYT and UBACYT.