Title
Stabilization versus inhibition of TAFIa by competitive inhibitors in vitro
Author
Gaubius Instituut TNO
Walker, J.B.
Hughes, B.
James, I.
Haddock, P.
Kluft, C.
Bajzar, L.
Publication year
2003
Abstract
Two competitive inhibitors of TAFIa (activated thrombin-activable fibrinolysis inhibitor), 2-guanidinoethyl-mercaptosuccinic acid and potato tuber carboxypeptidase inhibitor, variably affect fibrinolysis of clotted human plasma. Depending on their concentration, the inhibitors shortened, prolonged, or had no effect on lysis in vitro. The inhibitor-induced effects were both tissue-type plasminogen activator (tPA) and TAFIa concentration-dependent. Inhibitor-dependent prolongation was favored at lower tPA concentrations. The magnitude of the prolongation increased with TAFIa concentration, and the maximal prolongation observed at each TAFIa concentration increased saturably with respect to TAFIa. A theoretical maximal prolongation of 20-fold was derived from a plot of the maximum prolongation versus TAFIa. This represents, for the first time, a measurement of the maximal antifibrinolytic potential of TAFIa in vitro. Because TAFIa spontaneously decays, the stabilization of TAFIa was investigated as a mechanism explaining the inhibitor-dependent prolongation of lysis. Both inhibitors stabilized TAFIa in a concentration-dependent, non-saturable manner. Although their KI values differed by three orders of magnitude, TAFIa was identically stabilized when the fraction of inhibitor-bound TAFIa was the same. The data fit a model whereby only free TAFIa decays. Therefore, the variable effects of competitive inhibitors of TAFIa on fibrinolysis can be rationalized in terms of free TAFIa and lysis time relative to the half-life of TAFIa.
Subject
Biomedical Research
Chemical activation
Tissue
Competitive inhibitors
Biochemistry
2 guanidinoethylmercaptosuccinic acid
Potato tuber carboxypeptidase inhibitor
Thrombin activatable fibrinolysis inhibitor
Tissue plasminogen activator
Unclassified drug
3 (2 guanidinoethyl) 2 mercaptosuccinic acid
Carboxypeptidase
Carboxypeptidase inhibitor, plant
Succinic acid derivative
Vegetable protein
Blood clotting
Competitive inhibition
Concentration response
Enzyme kinetics
Enzyme stability
Half life time
In vitro study
Potato
Protein stability
Binding competition
Chemistry
Dose response
Drug antagonism
Metabolism
Theoretical model
Solanum tuberosum
Binding, Competitive
Carboxypeptidase U
Carboxypeptidases
Dose-Response Relationship, Drug
Enzyme Inhibitors
Fibrinolysis
Humans
Kinetics
Models, Theoretical
Plant Proteins
Protein Binding
Succinates
Temperature
Time Factors
Tissue Plasminogen Activator
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http://resolver.tudelft.nl/uuid:0980bcd0-cbe2-4986-b799-8190a2d8637a
DOI
https://doi.org/10.1074/jbc.m205006200
TNO identifier
237005
ISSN
0021-9258
Source
Journal of Biological Chemistry, 278 (278), 8913-8921
Document type
article