Characterization of an ATP diphosphohydrolase activity (APYRASE, EC 3.6.1.5) in rat blood platelets

In the present report we describe an apyrase (ATP diphosphohydrolase, EC 3.6.1.5) in rat blood platelets. The enzyme hydrolyses almost identically quite different nucleoside di- and triphosphates. The calcium dependence and pH requirement were the same for the hydrolysis of ATP and ADP and the appar...

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Bibliographic Details
Published in:Molecular and cellular biochemistry 1993-12, Vol.129 (1), p.47-55
Main Authors: FRASSETTO, S. S, DIAS, R. D, SARKIS, J. J. F
Format: Article
Language:English
Subjects:
Adenosine - blood
Adenosine Diphosphate - blood
Adenosine Triphosphate - blood
Analytical, structural and metabolic biochemistry
Animals
Apyrase - antagonists & inhibitors
Apyrase - blood
Biological and medical sciences
Blood coagulation. Blood cells
Blood Platelets - enzymology
Enzymes and enzyme inhibitors
Fundamental and applied biological sciences. Psychology
Hydrogen-Ion Concentration
Hydrolases
Hydrolysis
Kinetics
Male
Molecular and cellular biology
Platelet
Rats
Rats, Wistar
Substrate Specificity
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Summary:In the present report we describe an apyrase (ATP diphosphohydrolase, EC 3.6.1.5) in rat blood platelets. The enzyme hydrolyses almost identically quite different nucleoside di- and triphosphates. The calcium dependence and pH requirement were the same for the hydrolysis of ATP and ADP and the apparent Km values were similar for both Ca(2+)-ATP and Ca(2+)-ADP as substrates. Ca(2+)-ATP and Ca(2+)-ADP hydrolysis could not be attributed to the combined action of different enzymes because adenylate kinase, inorganic pyrophosphatase and nonspecific phosphatases were not detected under our assay conditions. The Ca(2+)-ATPase and Ca(2+)-ADPase activity was insensitive to ATPase, adenylate kinase and alkaline phosphatase classical inhibitors, thus excluding these enzymes as contaminants. The results demonstrate that rat blood platelets contain an ATP diphosphohydrolase involved in the hydrolysis of ATP and ADP which are vasoactive and platelet active adenine nucleotides.
ISSN:0300-8177
1573-4919
DOI:10.1007/BF00926575