Features of plasminogen activation in a complex with antiplasminogen monoclonal antibody IV-1C

Antiplasminogen monoclonal antibody IV-1c (IV-1c) with antigenic determinant in V709-G718 site of plasminogen (Pg) protease domain (Druzhina N.N. et al. 1996.) can induce catalytic activity in Pg moiety of the complex. Catalytic activity appeared in Pg-IV-1c complex after approximately 2 h lag-period. Rate of Lys-Pg activation was higher then that of Glu-Pg. Amidolytic activity of Pg-SK equimolar complex was completely inhibited by IV-1c at 2:1 = Pg:IV-1c molar ratio. At constant Glu-Pg concentration increasing of the IV-1c concentration to equimolar of Pg accelerated Pg activation. Subsequent increase of IV-1c concentration inhibited the Pg activation sharply. Increasing of Glu-Pg concentration at constant IV-1c one did not inhibit Glu-Pg activation in Pg-IV-1c complex. The rate dependence of Pg activation from Glu-Pg-IV-1c complex concentration curve had bell-shaped form with maximum at 500 nM. Electrophoretic analysis of components of Glu-Pg-IV-1c complex showed that Lys-Pg and Lys-Pm were not observed at 100 nM complex concentration for 6 h period of reaction. At 680 nM concentration Glu-Pg-IV-1c complex these forms appeared in initial moments of reaction activation after lag-period. Kinetic scheme and peculiarities of Pg activation reaction in Pg-IV-1c complex are discussed.