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Type: Artigo de periódico
Title: Purification And Kinetic Properties Of A Castor Bean Seed Acid Phosphatase Containing Sulfhydryl Groups
Author: Granjeiro P.A.
Ferreira C.V.
Granjeiro J.M.
Taga E.M.
Aoyama H.
Abstract: An acid phosphatase (EC has been identified and purified from castor bean (Ricinus communis L., IAC-80) seed through sulphopropyl (SP)-Sephadex, diethylaminoethyl (DEAE)-Sephadex, Sephacryl S-200, and Concanavalin A-Sepharose chromatography. The enzyme was purified 2000-fold to homogeneity, with a final specific activity of 3.8 μkat mg-1 protein. The purified enzyme revealed a single diffuse band with phosphatase activity on nondenaturing polyacrylamide gel electrophoresis, at pH 8.3. The relative molecular mass, determined by high-performance liquid chromatography (HPLC), was found to be 60 kDa. The acid phosphatase had a pH optimum of 5.5 and an apparent K(m) value for p-nitrophenylphosphate of 0.52 mM. The enzyme-catalyzed reaction was inhibited by inorganic phosphate, fluoride, vanadate, molybdate, p-chloromercuribenzoate (pCMB), Cu2+ and Zn2+. The strong inhibition by pCMB, Cu2+ and vanadate suggests the presence of sulfhydryl groups essential for catalysis. The castor bean enzyme also recognized tyrosine-phosphate and inorganic pyrophosphate (PP(i)) as substrate. The highest specificity constant (V(max)/K(m)) was observed with PP(i), making it a potential physiological substrate.
Rights: fechado
Identifier DOI: 10.1034/j.1399-3054.1999.100201.x
Date Issue: 1999
Appears in Collections:Unicamp - Artigos e Outros Documentos

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