PMID- 15206937
OWN - NLM
STAT- MEDLINE
DCOM- 20040823
LR  - 20161017
IS  - 0014-2956 (Print)
IS  - 0014-2956 (Linking)
VI  - 271
IP  - 13
DP  - 2004 Jul
TI  - Altered inactivation pathway of factor Va by activated protein C in the presence 
      of heparin.
PG  - 2724-36
AB  - Inactivation of factor Va (FVa) by activated protein C (APC) is a predominant 
      mechanism in the down-regulation of thrombin generation. In normal FVa, 
      APC-mediated inactivation occurs after cleavage at Arg306 (with corresponding 
      rate constant k'306) or after cleavage at Arg506 (k506) and subsequent cleavage 
      at Arg306 (k306). We have studied the influence of heparin on APC-catalyzed FVa 
      inactivation by kinetic analysis of the time courses of inactivation. Peptide 
      bond cleavage was identified by Western blotting using FV-specific antibodies. In 
      normal FVa, unfractionated heparin (UFH) was found to inhibit cleavage at Arg506 
      in a dose-dependent manner. Maximal inhibition of k506 by UFH was 12-fold, with 
      the secondary cleavage at Arg306 (k306) being virtually unaffected. In contrast, 
      UFH stimulated the initial cleavage at Arg306 (k'306) two- to threefold. Low 
      molecular weight heparin (Fragmin) had the same effects on the rate constants of 
      FVa inactivation as UFH, but pentasaccharide did not inhibit FVa inactivation. 
      Analysis of these data in the context of the 3D structures of APC and FVa and of 
      simulated APC-heparin and FVa-APC complexes suggests that the heparin-binding 
      loops 37 and 70 in APC complement electronegative areas surrounding the Arg506 
      site, with additional contributions from APC loop 148. Fewer contacts are 
      observed between APC and the region around the Arg306 site in FVa. The modeling 
      and experimental data suggest that heparin, when bound to APC, prevents optimal 
      docking of APC at Arg506 and promotes association between FVa and APC at position 
      Arg306.
FAU - Nicolaes, Gerry A F
AU  - Nicolaes GA
AD  - Department of Biochemistry, Cardiovascular Research Institute Maastricht, The 
      Netherlands. G.Nicolaes@Bioch.Unimaas.nl
FAU - Sorensen, Kristoffer W
AU  - Sorensen KW
FAU - Friedrich, Ute
AU  - Friedrich U
FAU - Tans, Guido
AU  - Tans G
FAU - Rosing, Jan
AU  - Rosing J
FAU - Autin, Ludovic
AU  - Autin L
FAU - Dahlback, Bjorn
AU  - Dahlback B
FAU - Villoutreix, Bruno O
AU  - Villoutreix BO
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Eur J Biochem
JT  - European journal of biochemistry
JID - 0107600
RN  - 0 (Protein C)
RN  - 65522-14-7 (Factor Va)
RN  - 9005-49-6 (Heparin)
SB  - IM
MH  - Blotting, Western
MH  - Catalysis
MH  - Crystallography, X-Ray
MH  - Factor Va/*antagonists & inhibitors
MH  - Heparin/*pharmacology
MH  - Kinetics
MH  - Models, Molecular
MH  - Protein C/*physiology
EDAT- 2004/06/23 05:00
MHDA- 2004/08/24 05:00
CRDT- 2004/06/23 05:00
PHST- 2004/06/23 05:00 [pubmed]
PHST- 2004/08/24 05:00 [medline]
PHST- 2004/06/23 05:00 [entrez]
AID - EJB4201 [pii]
AID - 10.1111/j.1432-1033.2004.04201.x [doi]
PST - ppublish
SO  - Eur J Biochem. 2004 Jul;271(13):2724-36. doi: 10.1111/j.1432-1033.2004.04201.x.