Effect of the cyanogen-bromide-2 fragment of fibrinogen on plasminogen activation by single-chain urokinase-type plasminogen activator.
Activation of Glu-plasminogen by single-chain urokinase-type plasminogen activator (sc-uPA), isolated from human urine, was studied in a purified system in the absence and presence of the cyanogen bromide fibrinogen fragment, FCB 2, and compared to plasminogen activation by two-chain high-Mr urokinase. Plasminogen activation by sc-uPA was significantly increased by the FCB-2 fibrinogen fragment, an effect brought about by decrease of apparent Km and increase of apparent kcat. During the course of plasminogen activation by scu-PA, two-chain urokinase was formed from 125I-sc-uPA to a significant degree only when a concentration of 30 nM plasmin was reached in the incubation mixture; this was only the case in the system stimulated by FCB-2 fibrinogen fragment and only after 30 min. Formation of two-chain urokinase was not, however, related to the increase in the rate of plasmin formation induced by the FCB-2 fibrinogen fragment.
D003488:Cyanogen Bromide; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010446:Peptide Fragments / Q000378:metabolism*; D010958:Plasminogen / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000302:isolation & purification / Q000378:metabolism* / Q000652:urine
D046911:Macromolecular Substances; D010446:Peptide Fragments; D005340:Fibrinogen; D010958:Plasminogen; D014568:Urokinase-Type Plasminogen Activator; D003488:Cyanogen Bromide