The Lipolytic Activity of Antithrombin III

Antithrombin III in the circulating blood is known to play an important role on the coagulation mechanism of the blood and is reported to be decreased in its amount on the cases of myocardial infarction and arteriosclerosis, in the meanwhile the arteriosclerosis has been considered to be one of thrombogenic factors. This research was designed to investigate the effects of antithrombin III on the relationship between fibrin formation and atherosclerosis.

Antithrombin III was purified from human defibrinated plasma by Heparin Sepharose Affinity Chromatography. Using this antithrombin III as an enzyme, its lipolytic activity was assayed spectrophotometrically detecting the produced free fatty acid from various substrates, Intralipid, Triolein, and Human Chylomicron respectively. Lipoprotein lipase activity was detected in the purified antithrombin III. Intralipid was hydrolyzed to a greater extent than triolein or chylomicron and it is concluded that antithrombin III in the circulating blood has not only the inhibitory activity of thrombin but also has the lipolytic activity. From these observations it is considered that this lipolytic activity is beneficial for preventing the developement of atherosclerosis and also of thrombosis.