A specific, photolabile and irreversible antagonist (L662,025) of the PAF-receptor |
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Authors: | I M Hussaini T Y Shen |
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Institution: | Department of Chemistry, University of Virginia, Charlottesville 22901. |
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Abstract: | PAF (0.2 microM) induced maximal platelet aggregation in human PRP and 3H]-PAF (1-5 nM) binding to platelet membrane preparations had Kd value of 3.8 nM and Bmax of 200 fmoles/mg of protein. Without UV irradiation, a synthetic azido tetrahydrofuran derivative L662,025 was a reversible and competitive PAF-receptor antagonist with IC50 values of 5.6 +/- 0.3 microM (platelet aggregation) and 1.0 +/- 0.25 microM (receptor binding). Photolysis of L662,025 in the presence of PRP produced an irreversible inhibition of platelet aggregation and specific binding of 3H]-PAF (1 nM). L662,025 did not affect collagen- or ADP-induced human platelet aggregation before or after photolysis. It is a new probe that can be used to identify and characterize the PAF-receptor. |
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