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Free radical‐induced inhibition of ATP diphosphohydrolase activity (EC 3.6.1.5) from rat blood platelets
Author(s) -
Frassetto Silvana S.,
Dias Renato D.,
Sarkis João J. F.
Publication year - 1997
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549700201161
Subject(s) - apyrase , trolox , chemistry , platelet , glutathione , biochemistry , lipid peroxidation , enzyme , tbars , vitamin e , platelet activation , antioxidant , immunology , biology , dpph
In the present report we demonstrate the in vitro effects of free radicals on an ecto‐ATP diphosphohydrolase activity (apyrase, EC 3.6.1.5) from rat blood platelets. Rat blood platelets were exposed to an oxidant‐generating system (H202 / Fe2+ / ascorbate) and the ATP diphosphohydrolase activity was inhibited. The enzyme inhibition was prevented by glutathione (GSH) and cysteine but not by trolox as a vitamin E analogue. The TBARS (thiobarbituric acid reactive substances) assay and the determination of sulphydryl groups indicate that the inhibition of the enzyme activity in resting platelets is not related to lipid peroxidation or to oxidation of sulphydryl residues. These results demonstrate the susceptibility of ATP diphosphohydrotase activity from platelets to free radicals and suggest that amino acid residues which are essential for the enzyme function are probably modified.