The formation of complexes between human plasminogen activator inhibitor-1 (PAI-1) and sodium dodecyl sulfate: possible implication in the functional properties of PAI-1.
The effect of the anionic detergent sodium dodecyl sulfate (SDS) on human PAI-1 present in plasma, platelet extracts and endothelial cell cultures, was examined. Using the dye partitional extraction method of Mukerjee [1956) Anal. Chem. 28, 870-873) to quantitate ionic surfactants, and a discontinuous spectrophotometric assay for the titration of PAI-1 based on the measurement of residual active t-PA, we found (i) that SDS remains tightly bound to PAI-1 after equilibrium dialysis and (ii) that the activity of the latter was closely related to the amount of SDS carried over by the PAI-1 solution. The highest concentrations of SDS (ratio of SDS to protein greater than 0.1) were detected in the platelet-derived sources of PAI-1 which also showed the lowest residual t-PA activity. Moreover, it is demonstrated by SDS-PAGE and autoradiography that the tight binding of SDS to PAI-1 decreases its ability to form complexes with t-PA. Similar results were obtained with PAI-1 previously inactivated at 37 degrees C: the inability of PAI-1 to form complexes with t-PA was unchanged after SDS treatment. These observations suggest that the decrease in the residual activity of t-PA observed with the SDS-treated PAI-1 preparations is not related to an increase in the inhibitory activity of PAI-1. In fact, SDS was able to produce a decrease in both the binding of t-PA to fibrin and the activation of plasminogen by fibrin-bound t-PA. Bovine PAI-1 has been shown to exist in a latent SDS-activatable form. Our data indicate that such a form might not be present in the human sources of PAI-1 we have tested.
Gaussem
P
P
Institut National de la Santé et de la Recherche Médicale, Hôpital de Bicêtre, France.
Anglés-Cano
E
E
D001792:Blood Platelets / Q000378:metabolism; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000378:metabolism; D005337:Fibrin / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D015849:Plasminogen Inactivators / Q000378:metabolism*; D011485:Protein Binding; D012967:Sodium Dodecyl Sulfate / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000378:metabolism
D015849:Plasminogen Inactivators; D012967:Sodium Dodecyl Sulfate; D005337:Fibrin; D010959:Tissue Plasminogen Activator