Open AccessInfluence of cyanogen‐bromide‐digested fibrinogen on the kinetics of plasminogen activation by urokinase
Author(s) -
LIJNEN H. Roger,
HOEF Berthe,
COLLEN Désiré
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08499.x
Subject(s) - cyanogen bromide , urokinase , chemistry , kinetics , fibrinogen , enzyme kinetics , plasminogen activator , plasmin , fibrinolysis , biochemistry , enzyme , medicine , peptide sequence , active site , physics , quantum mechanics , gene
The catalytic efficiency ( k cat / K m ) of high‐molecular‐mass urokinase for the activation of Glu‐plasminogen is increased about 10‐fold in the presence of CNBr‐digested fibrinogen. This stimulation is similar to that observed with 6‐aminohexanoic acid, and yields kinetic parameters comparable to those for the activation of Lys‐plasminogen by urokinase. The increase of the activation rate of Glu‐plasminogen by urokinase in the presence of CNBr‐Fg can thus be explained by a conformational change in the plasminogen molecule similar to that observed upon conversion of Glu‐plasminogen to Lys‐plasminogen and upon binding of 6‐aminohexanoic acid to Glu‐plasminogen. Stabilization of the Michaelis complex between urokinase and plasminogen by formation of a cyclic ternary complex with CNBr‐Fg, which has been invoked to explain the dramatic stimulatory effect of CNBr‐Fg on the activation of plasminogen by tissue‐type plasminogen activator, does not appear to play a significant role in the increased activation rate.