title: Kinetic studies of the urokinase catalysed conversion of NH2-terminal lysine plasminogen to plasmin.
abstract: A method for determining initial velocities of the urokinase (EC 3.4.99.26) catalysed converstion of NH2-terminal lysine plasminogen to plasmin (EC 3.4.21.7) is presented. This reaction has been coupled with the hydrolysis of alpha-N-benzyoly-L-arginine ethyl ester, which is catalysed by plasmin, and its rate has been determined from the time course of the overall reaction. The proenzyme-enzyme conversion was found to obey the Michaelis-Menten rate equation. The following values of the kinetic parameters were obtained: the apparent Michaelis constant, Km = 40.7 +/- 6.2 muM; the catalytic constant, kc = 2.59+/-0.31 s(-1), and kc/Km = 6.36-10(4) +/- 0.24-10(4) M(-1)-s(-1).
mesh_terms: D010450:Endopeptidases / Q000378:metabolism*; D005341:Fibrinolysin / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008239:Lysine; D008433:Mathematics; D010958:Plasminogen / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
chemical_list: D010958:Plasminogen; D010450:Endopeptidases; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; D008239:Lysine