IMPORTANCES OF POLAR GROUPS FOR INITIATING BLOOD COAGULATION AND AGGREGATING PLATELETS

HAEMOSTASIS and thrombosis are thought to involve a reaction between the blood and the diseased or damaged walls of blood vessels, but little is known about the chemical nature of the process. It is, however, known that collagen, which is present in the walls of blood vessels, will aggregate platelets in vitro1,2 and will also initiate the blood clotting mechanism3,4. These properties of native collagen with an intact triple helical structure are, however, lacking in the denatured random coil form4,5. Furthermore, selective blocking of polar groups on the native collagen molecule specifically inhibits either the ability to aggregate platelets or to initiate clotting. In the light of these and other observations listed in Tables 1 and 2, we wish to propose that rigidly spaced polar groups confer on substances the ability to aggregate platelets or to initiate clotting by activating the Hageman factor. © 1969 Nature Publishing Group.