A study of the interaction between Helicobacter pylori and components of the human fibrinolytic system.
The interaction of plasminogen, tissue plasminogen activator (t-PA) and urokinase with a clinical strain of Helicobacter pylori was studied. Plasminogen bound to the surface of H. pylori cells in a concentration-dependent manner and could be activated to the enzymatic form, plasmin, by t-PA. Affinity chromatography assays revealed a plasminogen-binding protein of 58.9 kDa in water extracts of surface proteins. Surface-associated plasmin activity, detected with the chromogenic substrate CBS 00.65, was observed only when plasminogen and an exogenous activator were added to the cell suspension. The two physiologic plasminogen activators, t-PA and urokinase, were also shown to bind to and remain active on the surface of bacterial cells. epsilon-Aminocaproic acid caused partial inhibition of t-PA binding, suggesting that the kringle 2 structure of this activator is involved in the interaction with surface receptors. The activation of plasminogen by t-PA, but not urokinase, strongly depended on the presence of cells and a 25-fold enhancer effect on the initial velocity of activation by t-PA compared to urokinase was established. Furthermore, a relationship between cell concentration and the initial velocity of activation was demonstrated. These findings support the concept that plasminogen activation by t-PA on the bacterial surface is a surface-dependent reaction which offers catalytic advantages.
Yarzábal
A
A
Laboratorio de Biología y Medicina Experimental, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
Avilán
L
L
Hoelzl
K
K
de Muñoz
M
M
Puig
J
J
Kansau
I
I
D000614:Aminocaproates / Q000378:metabolism; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D005343:Fibrinolytic Agents / Q000378:metabolism*; D016480:Helicobacter pylori / Q000378:metabolism*; D006801:Humans; D007202:Indicators and Reagents; D010960:Plasminogen Activators / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D000614:Aminocaproates; D005343:Fibrinolytic Agents; D007202:Indicators and Reagents; D011956:Receptors, Cell Surface; D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator