[Endoperoxide prostaglandin synthetase from the microsomal fraction of human platelets].

The reaction of oxidation of arachidonic acid by the enzymes localized in the microsomal fraction of human platelet was investigated. It was shown that the preparations of washed microsomes are devoid of the lipoxygenase activity but possess the endoperoxideprostaglandin synthetase activity. The oxidation of arachidonic acid is a three substrates process, whose indispensable component is a reducing agent, i. e. an electron donor. The stoichiometry of the three substrates reaction as well as the dependence of the reaction rate on the concentration of O2, arachidonic acid and the electron donor, haemin were studied. The effective values of some reaction parameters were determined.