Covalent binding of eicosanoids to platelet proteins.

Following an incubation of washed human platelets with 14C-arachidonic acid, a small fraction of the radioactivity became tightly bound to the protein pellet. Three criteria suggested that it was actually a covalent binding: it was not removed by exhaustive extractions with solvents of various polarities, it was not dialysable against SDS-buffer and it corresponded to the labeling of several protein bands after SDS-polyacrylamide gel electrophoresis. The use of several pharmacological agents (indomethacin, eicosatetraynoic acid, dazoxiben, diamide) has allowed us to divide this binding into three components: the first one, independent from both cyclooxygenase and lipoxygenase, the second one dependent on cyclooxygenase products and finally the third one, dependent on lipoxygenase products.