PLASMINOGEN-PLASMIN SYSTEM .V. A STOICHIOMETRIC EQUILLIBRIUM COMPLEX OF PLASMINOGEN AND A SYNTHETIC INHIBITOR

The interaction between plasminogen and trans-AMCHA (trans-4-aminomethylcyclohexanecarboxylic acid) was investigated using ultracentrifugal and gel filtration techniques. trans-AMCHA was found to alter the sedimentation behavior of plasminogen with a critical concentration of about 0.1 mM at pH 7.5 without dissociation of the plasminogen molecule and to bind to plasminogen with a dissociation constant of 0.085 mM. Such effects were specific for trans-AMCHA and also for ε-aminocaproic acid. From the comparison of these findings with the inhibitory actions of trans-AMCHA and ε-aminocaproic acid on the activation of plasminogen, it was concluded that these compounds inhibited the activation through the formation of a stoichiometric equilibrium complex with plasminogen, accompanying a conformational change of the plasminogen molecule. © 1969.