Kinetic characteristics of fibrinogen and fibrin hydrolysis by plasmin 1 and 2 and miniplasmin

Abstract Fibrinogen and fibrin hydrolysis by native plasmin 1 and 2 and by miniplasmin was studied. The degree of hydrolysis was estimated by the number of amino groups determined with trinitrobenzene sulphonic acid. The process was shown to obey Michaelis-Menten kinetics. Kinetic parameters of fibrinogen and fibrin hydrolysis by plasmin forms 1 and 2 were identical (K M = 6.5 × 10 −6 M, k cat = 7.1 sec −1 while for hydrolysis by miniplasmin K M = 20.0 × 10 −6 M, k cat = 3.58 sec −1 . Thus, it was demonstrated that enzymatic properties of plasmin are to some extent dependent on the presence of lysine-binding sites. However, this appears not to have a decisive effect on fibrinolytic process.