Biochemical characterization and inhibitory effects of dinophysistoxin-1, okadaic acid and microcystine 1-r on protein phosphatase 2a purified from the mussel Mytilus chilensis

Rivas, M; Garcia C.; Liberona J.L.; Lagos, N.

Keywords: chemistry, enzymology, acid, performance, isolation, chromatography, enzyme, purification, animals, pressure, electrophoresis, liquid, gel, inhibitor, bivalvia, drug, antagonism, inhibitors, article, bivalve, phosphatase, phosphoprotein, dinophysistoxin, animal, polyacrylamide, 1, derivative, microcystins, cyclic, Electrophoresis,, cyclopeptide, Peptides,, and, High, Chromatography,, cyanoginosin, lr, okadaic, pyran, Pyrans

Abstract

Protein phosphatases are involved in many cellular processes. One of the most abundant and best studied members of this class is protein phosphatase type-2A (PP2A). In this study, PP2A was purified from the mussel Mytilus chilensis. Using both SDS-PAGE and size exclusion gel filtration under denaturant conditions, it was confirmed that the PP2A fraction was essentially pure. The isolated enzyme is a heterodimer and the molecular estimated masses of the subunits are 62 and 28 kDa. The isolated PP2A fraction has a notably high p-NPP phosphatase activity, which is inhibited by NaCl. The hydrolytic p-NPP phosphatase activity is independent of the MgCl, concentration. The time courses of the inhibition of the PP2A activity of p-NPP hydrolysis by increasing concentrations of three phycotoxins that are specific inhibitors of PP2A are shown. Inhibitions caused by Okadaic acid, dinophysistoxin-1 (DTX1, 35-methylokadiac acid) and Microcystine L-R are dose-dependent with inhibition constants (Ki) of 1.68, 0.40 and 0.27 nM respectively. Microcystine L-R, the most potent phycotoxin inhibitor of PP2A isolated from Mytilus chilensis with an IC50 = 0.25 ng/ml, showed the highest specific inhibition effect an the p-NPP hydrolisis. The calculated IC50 for DTX1 and OA was 0.75 ng/ml and 1.8 ng/ml respectively.

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Título según SCOPUS: Biochemical characterization and inhibitory effects of dinophysistoxin-1, okadaic acid and microcystine 1-r on protein phosphatase 2a purified from the mussel Mytilus chilensis
Título de la Revista: BIOLOGICAL RESEARCH
Volumen: 33
Número: 3
Editorial: SOC BIOLGIA CHILE
Fecha de publicación: 2000
Página de inicio: 197
Página final: 206
Idioma: English
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-0003816827&partnerID=q2rCbXpz
Notas: SCOPUS