Purificação e caracterização de fosfatase acida da semente de mamona (Ricinus communis)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The acid phosphatase (E.C. 3.1.3.2) AP1 form has been detected and partially purified from castor bean (Ricinus communis) seeds through SP-Sephadex, DEAE-Sephadex, Sephacry1 S-200 and Concanavalin. A chromatographies. The enzyme was purified to homogenity 2,100-fold, with a specific activity of 230 mmol min-1 . Relative molecular mass, determined by Shim pack diol150 column (Shimadzu HPLC), was found to be 60 KDa. AP1 presented a carbohydrate moiety in its proteic structure and binds to concanavalin A Sepharose. The fraction revealed a single phosphatase activity diffuse band on nondenaturing polyacrylamide gel electrophoresis, at pH 8.3. The acid phosphatase purified from castor bean seeds studied here presented a high activity at pH 5.5. An apparent Km of 0.52 mM was found for p nitrophenylphosphate, at pH 5.5 and 37°C. Using pNPP as substrate, no effect was observed on the acid phosphatase activity in the presence of EDT A, dithiothreitol, and b-mercaptoethanol. The enzyme was inhibited by inorganic phosphate, fluoride, vanadate, molybdate, CU2+ and Zn2+. The castor bean seeds acid phosphatase did not catalyze the transphosphorylation reaction since no stimulation was observed with inorganic phosphate acceptors, such as glycerol, methanol and ethanol

ASSUNTO(S)

enzimas cinetica de enzimas plantas

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