Specific glycosaminoglycans support the inhibition of thrombin by plasminogen activator inhibitor 1.
In the absence of accessory components, plasminogen activator inhibitor 1 (PAI-1) rapidly forms equimolar, inactive complexes both with tissue-type (t-PA) and with urokinase-type (u-PA) plamsinogen activator. In the presence of either the glycoprotein vitronectin or the glycosaminoglycan heparin, PAI-1 is endowed with additional, efficient thrombin-inhibitory properties (Ehrlich et al., 1990, 1991a). Here, we have investigated the interaction between PAI-1, thrombin, and glycosaminoglycans in more detail. Inhibition of thrombin by PAI-1 was quantitatively analyzed in the presence of a wide range of concentrations of heparin, heparan sulfate, dermatan sulfate, chondroitin 4-sulfate, chondroitin 6-sulfate, keratan sulfate, and hyaluronic acid by measuring residual amidolytic activity. In addition, a qualitative analysis was performed by determining the formation of SDS-stable, equimolar complexes between thrombin and PAI-1 in the presence of various glycosaminoglycans. Heparin, at concentrations between 0.1 and 1 microgram/mL, significantly promoted thrombin inhibition by PAI-1 as well as SDS-stable complex formation. Suboptimal inhibition was observed with dermatan sulfate, chondroitin 4-sulfate, and heparan sulfate at concentrations that are at least 1 order of magnitude higher than that required for optimal inhibition in the presence of heparin. Virtually no inhibition of thrombin and SDS-stable complex formation was detected with any of the other glycosaminoglycans at concentrations between 0.1 and 1 microgram/mL.(ABSTRACT TRUNCATED AT 250 WORDS)
Gebbink
R K
RK
Department of Molecular Biology, Central Laboratory of The Netherlands Red Cross Blood Transfusion Service, Amsterdam.
Reynolds
C H
CH
Tollefsen
D M
DM
Mertens
K
K
Pannekoek
H
H
D004591:Electrophoresis, Polyacrylamide Gel; D006025:Glycosaminoglycans / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D017395:Plasminogen Activator Inhibitor 1 / Q000494:pharmacology*; D011485:Protein Binding; D013053:Spectrophotometry; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism
D006025:Glycosaminoglycans; D017395:Plasminogen Activator Inhibitor 1; D013917:Thrombin