The Isolation of Human Platelet Factor

Human platelet factor V has been isolated using either a monoclonal or polyclonal antibody directed against human plasma factor V. The largest peptide observed upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of purified human platelet factor V comigrates with purified human plasma factor V. However. a significant portion of the isolated protein is represented by peptides of lower apparent molecular weight (Mj. These lower Mr species that copurify with platelet factor V have been shown to be platelet factor V components by their immunological cross-reactivity with monoclonal and polyclonal antibodies to purified human plasma factor V. Platelets isolated from whole blood drawn directly into inhibitors to prevent proteolysis and platelet activation demonstrate the pattern of fragmented platelet factor V. The components of purified platelet factor V demonstrate apparent Mr ranging between 1 1 5 K and 330 K and are