Lipoprotein a inhibits streptokinase-mediated activation of human plasminogen.
Lipoprotein a [Lp(a)] inhibits human plasminogen (Pg) conversion to plasmin (Pm) by streptokinase- (SK-) mediated activation. Kinetic and binding studies indicate that Lp(a) inhibits Pg activation by competitive and uncompetitive inhibition. Lp(a) competes with Pg for SK and forms a stable complex. Lp(a) does not, however, inhibit Pg activation by the proteolytic SK-Pm complex. The SK-Pg and SK-Pg(act) intermediate complexes are possible targets of the Lp(a) uncompetitive inhibition. The competitive inhibition constant (Kic) is 45 nM or 14 mg/dL, and the uncompetitive inhibition constant (Kiu) is 140 nM or 42 mg/dL, corresponding to physiologic and pathophysiologic Lp(a) concentrations, respectively.
Edelberg
J M
JM
Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710.
Gonzalez-Gronow
M
M
Pizzo
S V
SV
D002850:Chromatography, Gel; D006801:Humans; D007700:Kinetics; D017270:Lipoprotein(a); D008074:Lipoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010958:Plasminogen / Q000378:metabolism*; D010960:Plasminogen Activators; D011485:Protein Binding; D013300:Streptokinase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification
D017270:Lipoprotein(a); D008074:Lipoproteins; D010958:Plasminogen; D013300:Streptokinase; D010960:Plasminogen Activators