Characterization of fetal serum 5'-nucleotide phosphodiesterase: a novel function as a platelet aggregation inhibitor in fetal circulation.
The study was performed to indicate the ADPase activity of 5'-nucleotide phosphodiesterase (PDEase) from human umbilical cord blood serum and demonstrates the effect of this enzyme on ADP-induced platelet aggregation. The PDEase was purified by using p-nitrophenyl-5'-TMP as a substrate. The PDEase had a molecular weight of 128,000 daltons, and activity of 103 nmol/min/mg protein. The PDEase activity was inhibited by 5'-AMP, ADP, ATP. But 2'-AMP, 3'-AMP, 3':5' cAMP, and adenosine had no inhibiting effects. Kinetic analysis indicated that ADP was a competitive inhibitor with a Ki value of 4.05x10(-5) M. The enzyme was markedly inhibited by 1 mM EDTA. The ADPase activity of the PDEase was 7.79 nmol/min/mg protein. The hydrolized products of ADP by the PDE ase were AMP and phosphoric acid. The platelet aggregation by ADP was inhibited by the addition of the PDEase in the platelet-rich plasma.
Department of Obstetrics and Gynecology, Hamamatsu Medical Center, Japan.
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H
Sakura
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S
Nagashima
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A
Nakashima
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M
Maeda
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology; D001081:Apyrase / Q000494:pharmacology; D001667:Binding, Competitive; D005312:Fetal Blood / Q000201:enzymology*; D006801:Humans; D007231:Infant, Newborn; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000097:blood* / Q000187:drug effects / Q000502:physiology*; D010975:Platelet Aggregation Inhibitors / Q000097:blood
D010726:Phosphodiesterase Inhibitors; D010975:Platelet Aggregation Inhibitors; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D010727:Phosphoric Diester Hydrolases; D001081:Apyrase