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9 results on '"Thomassen, M. Christella L.G.D."'

2. Small Peptides Blocking Inhibition of Factor Xa and Tissue Factor-Factor VIIa by Tissue Factor Pathway Inhibitor (TFPI)

Author

Dockal, Michael, primary, Hartmann, Rudolf, additional, Fries, Markus, additional, Thomassen, M. Christella L.G.D., additional, Heinzmann, Alexandra, additional, Ehrlich, Hartmut, additional, Rosing, Jan, additional, Osterkamp, Frank, additional, Polakowski, Thomas, additional, Reineke, Ulrich, additional, Griessner, Andreas, additional, Brandstetter, Hans, additional, and Scheiflinger, Friedrich, additional

Published
2014
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5. A prothrombinase-based assay for detection of resistance to activated protein C

Author

Nicolaes, Gerry A.F., Nicolaes, Gerry A.F., Thomassen, M. Christella L.G.D., van Oerle, Rene, Hamulyak, Karly, Hemker, H. Coenraad, Tans, Guido, Rosing, Jan, Nicolaes, Gerry A.F., Nicolaes, Gerry A.F., Thomassen, M. Christella L.G.D., van Oerle, Rene, Hamulyak, Karly, Hemker, H. Coenraad, Tans, Guido, and Rosing, Jan

Published
1996

6. Activation of human factor V by Meizothrombin

Author

Tans, Guido, Tans, Guido, Nicolaes, Gerry A.F., Thomassen, M. Christella L.G.D., Hemker, H. Coenraad, van Zonneveld, Anton-Jan, Pannekoek, Hans, Rosing, Jan, Tans, Guido, Tans, Guido, Nicolaes, Gerry A.F., Thomassen, M. Christella L.G.D., Hemker, H. Coenraad, van Zonneveld, Anton-Jan, Pannekoek, Hans, and Rosing, Jan

Published
1994

8. The effect of phospholipids, calcium ions and protein S on rate constants of human factor Va inactivation by activated human protein C.

Author

Bakker, Harry M., Tans, Guido, Janssen-Claessen, Truus, Thomassen, M. Christella L.G.D., Hemker, H. Coenraad, Griffin, John H., and Rosing, Jan

Subjects
PHOSPHOLIPIDS, LIPIDS, OLEIC acid, CALCIUM, IONS, PROTEINS, BIOCHEMISTRY
Abstract

Rate constants for human factor Va inactivation by activated human protein C (APC) were determined in the absence and presence of Ca2+ ions, protein S and varying concentrations of phospholipid vesicles of different lipid composition. APC-catalyzed factor Va inactivation in free solution (in the presence of 2 mM Ca2+) was studied under first-order reaction conditions with respect to both APC and factor Va and was characterized by an apparent second-order rate constant of 6.1 x l05 M-1 s-1. Stimulation of APC-catalyzed factor Va inactivation by phospholipids was dependent on the concentration and composition of the phospholipid vesicles. Optimal acceleration (230-fold) of factor Va inactivation was observed with 10 µM phospholipid vesicles composed of 20 mol% dioleoylglycerophosphoserine (Ole2GroPSer) and 80 mol% dioleoylglycerophosphocholine (Ole2GroPCho). At higher vesicle concentrations and at higher molar fractions of Ole2GroPSer some inhibition of APC-catalyzed factor Va inactivation was observed. Membranes that contained anionic phospholipids other than phosphatidylserine also promoted factor Va inactivation. The ability of different anionic lipids to enhance factor Va inactivation increased in the order phosphatidylethanolamine < oleic acid < phosphatidie acid < phosphatidylglycerol < phosphatidylmethanol < phosphatidylserine. APC-catalyzed factor Va inactivation in the presence of phospholipid vesicles could be saturated with respect to factor Va and the reaction obeyed Michaelis-Menten kinetics. Both the Km for factor Va and the Vmax of factor Va inactivation were a function of the phospholipid concentration. The Km increased from I nM at 2.5 µM phospholipid (Ole2GroPSer/Ole2GroPCho 20:80, mol/mol) to 65 nM at 250 µM phospholipid. The Vmax increased from 20 mol factor Va inactivated · min-1 · mol APC-1 at 2.5 µM phospholipid to 62 mol factor Va inactivated · min-1 · mol APC-1 at 10 µM phospholipid and remained constant at higher phospholipid concentrations. Protein S appeared to be a rather poor stimulator of APC-catalyzed factor Va inactivation. Protein-S-dependent rate enhancements were only observed in reaction mixtures that contained negatively charged phospholipid vesicles. Independent of the concentration and the lipid composition of the vesicles, protein S caused a twofold stimulation of APC-catalyzed factor Va inactivation. This suggests that, in the human system, enhancement of APC binding to phospholipid vesicles by protein S is of minor importance. Considering that protein S is a physiologically essential antithrombotic agent, it is likely that other factors or phenomena contribute to the in vivo antithrombotic action of protein S. [ABSTRACT FROM AUTHOR]

Published
1992
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9. Peptide Bond Cleavages and Loss of Functional Activity during Inactivation of Factor Va and Factor VaR506Qby Activated Protein C (∗)

Author

Nicolaes, Gerry A.F., Tans, Guido, Thomassen, M. Christella L.G.D., Hemker, H. Coenraad, Pabinger, Ingrid, Varadi, Katalin, Schwarz, Hans P., and Rosing, Jan

Abstract

Factor V was purified from the plasma of an activated protein C (APC)-resistant patient who is homozygous for the mutation Arg506→ Gln (factor VR506Q). Factor VR506Qwas converted by thrombin into factor Va which was further purified yielding a factor Va preparation that had the same cofactor activity in prothrombin activation as normal factor Va. Inactivation of low concentrations of normal factor Va (<5 nM) by 0.15 nM APC in the presence of phospholipid vesicles proceeded via a biphasic reaction that consisted of a rapid phase (k= 4.3 × 107M−1s−1), yielding a reaction intermediate with reduced cofactor activity that was fully inactivated during the subsequent slow phase (k= 2.3 × 106M−1s−1). Inactivation of factor VaR506Qproceeded via a monophasic reaction (k= 1.7 × 106M−1s−1). Immunoblot analysis showed that APC-catalyzed inactivation of factor Va occurred via peptide bond cleavages in the heavy chain. The rapid phase of inactivation of normal factor Va was associated with cleavage at Arg506and full inactivation of factor Va required subsequent cleavage at Arg306. The slow monophasic inactivation of factor VaR506Qcorrelated with cleavage at Arg306. Cleavage at Arg506in normal factor Va resulted in accumulation of a reaction intermediate that exhibited 40% cofactor activity in prothrombin activation mixtures that contained a high factor Xa concentration (5 nM). Compared with native factor Va, the reaction intermediate retained virtually no cofactor activity at low factor Xa concentrations (0.3 nM). This demonstrates that factor Va that is cleaved at Arg506is impaired in its ability to interact with factor Xa. Michaelis-Menten kinetic analysis showed that cleavage at Arg506in membrane-bound factor Va was characterized by a low Kmfor factor Va (20 nM) and kcat= 0.96 s−1. For cleavage at Arg306in factor VaR506Qthe kinetic parameters were Km= 196 nM and kcat= 0.37 s−1. This means that differences between APC-catalyzed inactivation of factors Va and VaR506Qbecome much less pronounced at high factor Va concentrations. When factor VaR506Qwas inactivated by APC in the absence of phospholipids, cleavage at Arg679of the heavy chain also contributed to factor Va inactivation. Comparison of rate constants for APC-catalyzed cleavage at Arg306, Arg506, and Arg679in the absence and presence of phospholipids indicated that phospholipids accelerated these cleavages to a different extent. This indicates that the binding of factor Va to phospholipids changes the accessibility of the cleavage sites and/or the sequence of peptide bond cleavage by APC.

Published
1995
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