scholarly journals Activated Protein C Cleavage of Factor Va Leads to Dissociation of the A2 Domain

1997 ◽  
Vol 272 (33) ◽  
pp. 20678-20683 ◽  
Author(s):  
Kenneth G. Mann ◽  
Matthew F. Hockin ◽  
Kelly J. Begin ◽  
Michael Kalafatis
Keyword(s):  
Protein C ◽  
Activated Protein C ◽  
Factor Va ◽  
A2 Domain

scholarly journals ptFVa ( Pseudonaja Textilis Venom-Derived Factor Va) Retains Structural Integrity Following Proteolysis by Activated Protein C

2021 ◽  
Author(s):  
Mark Schreuder ◽  
Xiaosong Liu ◽  
Ka Lei Cheung ◽  
Pieter H. Reitsma ◽  
Gerry A.F. Nicolaes ◽  
...  
Keyword(s):  
Protein C ◽  
Structural Integrity ◽  
Noncovalent Interactions ◽  
Activated Protein C ◽  
Regulatory Mechanisms ◽  
Factor V ◽  
Factor Va ◽  
Dynamics Simulations ◽  
A2 Domain

Objective: The Australian snake ptFV ( Pseudonaja textilis venom-derived factor V) variant that retains cofactor function despite APC (activated protein C)-dependent proteolysis. Here, we aimed to unravel the mechanistic principles by determining the role of the absent Arg306 cleavage site that is required for the inactivation of Fva (mammalian factor Va). Approach and Results: Our findings show that in contrast to human FVa, APC-catalyzed proteolysis of ptFVa at Arg306 and Lys507 does not abrogate ptFVa cofactor function. Remarkably, the structural integrity of APC-proteolyzed ptFVa is maintained indicating that stable noncovalent interactions prevent A2-domain dissociation. Using Molecular Dynamics simulations, we uncovered key regions located in the A1 and A2 domain that may be at the basis of this remarkable characteristic. Conclusions: Taken together, we report a completely novel role for uniquely adapted regions in ptFVa that prevent A2 domain dissociation. As such, these results challenge our current understanding by which strict regulatory mechanisms control FVa activity.

Dermatan Sulfate and LMW Heparin Enhance the Anticoagulant Action of Activated Protein C

1999 ◽  
Vol 82 (11) ◽  
pp. 1462-1468 ◽  
Author(s):  
José Fernández ◽  
Jari Petäjä ◽  
John Griffin
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Protein C ◽  
Dermatan Sulfate ◽  
Anticoagulant Activity ◽  
Activated Protein C ◽  
Factor V ◽  
Factor Va ◽  
Anticoagulant Action

SummaryUnfractionated heparin potentiates the anticoagulant action of activated protein C (APC) through several mechanisms, including the recently described enhancement of proteolytic inactivation of factor V. Possible anticoagulant synergism between APC and physiologic glycosaminoglycans, pharmacologic low molecular weight heparins (LMWHs), and other heparin derivatives was studied. Dermatan sulfate showed potent APC-enhancing effect. Commercial LMWHs showed differing abilities to promote APC activity, and the molecular weight of LMWHs correlated with enhancement of APC activity. Degree of sulfation of the glycosaminoglycans influenced APC enhancement. However, because dextran sulfates did not potentiate APC action, the presence of sulfate groups per se on a polysaccharide is not sufficient for APC enhancement. As previously for unfractionated heparin, APC anticoagulant activity was enhanced by glycosaminoglycans when factor V but not factor Va was the substrate. Thus, dermatan sulfate and LMWHs exhibit APC enhancing activity in vitro that could be of physiologic and pharmacologic significance.

A Novel Functional Assay of Protein C in Human Plasma and fts Comparison with Amidolytic and Anticoagulant Assays

1992 ◽  
Vol 67 (01) ◽  
pp. 046-049 ◽  
Author(s):  
H A Guglielmone ◽  
M A Vides
Keyword(s):  
Oral Anticoagulant ◽  
Protein C ◽  
Activated Protein C ◽  
Protein S ◽  
Normal Subjects ◽  
Test Sample ◽  
Functional Assay ◽  
Fast Method ◽  
Factor Va ◽  
Protein C Activity

SummaryA simple and fast method for the quantitative determination of protein C activity in plasma is here described. The first step consists in the conversion of protein C in the test sample into activated protein C by means of an activator isolated from Southern Copperhead venom. Subsequently, the degradation of factor Va, in presence of protein C-deficient plasma, is measured by the prolongation of the prothrombin time which is proportional to the amount of protein C in the sample. The dose-response curve showed a linear relationship from 6 to 150% protein C activity and the inter- and intra-assay reproducibility was 3.5% and 5.6% respectively. In normal subjects, a mean of protein C level of 98 ± 15% of normal pooled plasma was found. Comparison with the anticoagulant assay in samples of patients with oral anticoagulant, liver cirrhosis, disseminated intravascular coagulation and severe preeclampsia revealed an excellent correlation (r = 0.94, p <0.001). Also, a similar correlation (r = 0.93, p <0.001) existed between amidolytic assay and the method here proposed for all the samples studied without including the oral anticoagulant group. These results allowed us to infer that this method evaluates the ability of protein C to interact with protein S, phospholipids, calcium ions and factor Va.

scholarly journals Studies of the capacity of factor Xa to protect factor Va from inactivation by activated protein C.

1982 ◽  
Vol 257 (3) ◽  
pp. 1443-1447
Author(s):  
M.E. Nesheim ◽  
W.M. Canfield ◽  
W. Kisiel ◽  
K.G. Mann
Keyword(s):  
Protein C ◽  
Activated Protein C ◽  
Factor Xa ◽  
Factor Va

scholarly journals Binding of protein S to factor Va associated with inhibition of prothrombinase that is independent of activated protein C.

1993 ◽  
Vol 268 (4) ◽  
pp. 2872-2877
Author(s):  
M.J. Heeb ◽  
R.M. Mesters ◽  
G. Tans ◽  
J. Rosing ◽  
J.H. Griffin
Keyword(s):  
Protein C ◽  
Activated Protein C ◽  
Protein S ◽  
Factor Va

scholarly journals Factor V Is an Anticoagulant Cofactor for Activated Protein C during Inactivation of Factor Va

2009 ◽  
Vol 37 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Thomas J. Cramer ◽  
John H. Griffin ◽  
Andrew J. Gale
Keyword(s):  
Protein C ◽  
Activated Protein C ◽  
Factor V ◽  
Factor Va

Phospholipid-bound Tissue Factor Modulates both Thrombin Generation and APC-mediated Factor Va Inactivation

1999 ◽  
Vol 82 (12) ◽  
pp. 1673-1679 ◽  
Author(s):  
Katalin Váradi ◽  
Jürgen Siekmann ◽  
Peter Turecek ◽  
H. Peter Schwarz ◽  
Victor Marder
Keyword(s):  
Tissue Factor ◽  
Surface Density ◽  
Protein C ◽  
Thrombin Generation ◽  
Feedback Inhibition ◽  
Activated Protein C ◽  
Reaction System ◽  
Inverse Correlation ◽  
High Concentration ◽  
Factor Va

SummaryHemostasis is initiated by tissue factor (TF) exposed on cellular phospholipid (PL) membranes, leading to thrombin generation. The binding of thrombin to thrombomodulin (TM), activates the protein C pathway, resulting in the inactivation of factors Va and VIIIa by activated protein C (APC) and a negative feedback effect on thrombin generation. A new assay system was developed for simultaneous measurement of thrombin and APC generation in defibrinated plasma induced by large unilamellar PL vesicles complexed with full-length recombinant TF (TF:PL). TF:PL preparations with a low TF concentration induced an initial rate of thrombin generation below 100 nM/min, and resulted in less thrombin formation in the presence of TM than in its absence. In contrast, TF:PL preparations with a high concentration of TF induced a higher rate of thrombin generation, and APC-mediated feedback inhibition did not occur, despite maximal APC generation. We used the same TF:PL surfaces to study factor Va inactivation by APC in a non-plasma reaction system, and found an inverse correlation between TF surface density and the rate of factor Va inactivation. This observation suggests a previously unrecognized hemostatic effect of TF, namely a non-enzymatic surface density-based inhibition of the anticoagulant effect of APC. In this model, high concentrations and surface density of TF exert complementary effects by promoting the regular procoagulant cascade and by inhibiting the protein C pathway, thereby maximizing hemostasis after vascular injury.

Exosite-dependent regulation of factor VIIIa by activated protein C

Blood ◽  
2003 ◽  
Vol 101 (12) ◽  
pp. 4802-4807 ◽  
Author(s):  
Chandrashekhara Manithody ◽  
Philip J. Fay ◽  
Alireza R. Rezaie
Keyword(s):  
Protein C ◽  
Time Course ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Limited Proteolysis ◽  
Activated Protein C ◽  
Coagulation Cascade ◽  
Factor Va ◽  
Factor Viiia

AbstractActivated protein C (APC) is a natural anticoagulant serine protease in plasma that down-regulates the coagulation cascade by degrading cofactors Va and VIIIa by limited proteolysis. Recent results have indicated that basic residues of 2 surface loops known as the 39-loop (Lys37-Lys39) and the Ca2+-binding 70-80–loop (Arg74 and Arg75) are critical for the anticoagulant function of APC. Kinetics of factor Va degradation by APC mutants in purified systems have demonstrated that basic residues of these loops are involved in determination of the cleavage specificity of the Arg506 scissile bond on the A2 domain of factor Va. In this study, we characterized the properties of the same exosite mutants of APC with respect to their ability to interact with factor VIIIa. Time course of the factor VIIIa degradation by APC mutants suggested that the same basic residues of APC are also critical for recognition and degradation of factor VIIIa. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) of the factor VIIIa cleavage reactions revealed that these residues are involved in determination of the specificity of both A1 and A2 subunits in factor VIIIa, thus facilitating the cleavages of both Arg336 and Arg562 scissile bonds in the cofactor.

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