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Thrombin, the final serine protease in the clotting cascade, catalyzes the conversion of plasma fibrinogen to fibrin. Fibrin self-assembles into a fibrous mesh to form a soft clot that traps red blood cells to stop bleeding. Physiologically, thrombin’s numerous functions include positive feedback to amplify the clotting cascade, platelet activation, and involvement in wound healing and inflammation. In the laboratory, thrombin is also used to cleave fusion proteins created with a thrombin recognition site. We offer thrombin in lyophilized powder form from four different mammalian species. Each lot is standardized by the NIH clotting assay, and thrombin concentration is estimated from clotting times only in the range of 15-25 seconds. For researchers studying the effects of thrombin on cultured endothelial and other cells, Sigma supplies both bovine and human thrombins tested for cell culture. Convenient vials of about 10 units, sold in lots of ten, give insurance against loss of activity when active α-thrombin autolyzes to the β or γ forms that lack fibrinolytic activity.

Thrombin Technical Information

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T7513 Thrombin from bovine plasma lyophilized powder, ≥2,000 NIH units/mg protein (E1%/280 = 19.5)
T6634 Thrombin from bovine plasma lyophilized powder, 600-2,000 NIH units/mg protein (biuret)
T9549 Thrombin from bovine plasma powder, cell culture tested, ≥1,500 NIH units/mg protein (E1%/280 = 19.5)
T9000 Thrombin from bovine plasma buffered aqueous solution, ≥125 NIH units/mg protein (biuret)
T7009 Thrombin from human plasma lyophilized powder, ≥1,000 NIH units/mg protein (E1%/280, 18.3)
T1063 Thrombin from human plasma lyophilized powder, ≥2800 NIH units/mg protein (E1%/280, 18.3)
T4393 Thrombin from human plasma lyophilized powder, 1500-3500 NIH units/mg protein (E1%/280, 18.3), cell culture tested
T7572 Thrombin from human plasma 400-1000 NIH units/mg protein
T4897 Thrombin from rabbit plasma
T5772 Thrombin from rat plasma lyophilized powder, ≥1,000 units/mg protein (biuret)