Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.4.21.6 (
thromboplastin
)
13,278
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Factor III (
thromboplastin
) activity is inhibited by
apoB-100
, but the mechanism of inhibition is unknown. By examining the effect of purified
apoB-100
on factor III activity, we showed that
apoB-100
can inhibit factor III via a different mechanism from that caused by the issue-factor pathway-inhibitor, which is mainly carried on the surface of lipoproteins. Although the presence of calcium ions and factors X and VII may enhance the rate of inhibition, they are not a prerequisite for the inhibition of factor III by
apoB-100
. In addition, by investigating the changes in the UV spectra of
apoB-100
on interaction with factor III and factors X and VII and by assigning the shifts in absorption spectra to particular amino acids, we showed that these interactions involve negative and positive residues within these proteins. By following the rates of interactions between
apoB-100
and either factors III, X, VII, a two-step mechanism for the inhibition process involving factors X and VII was postulated. In this mechanism, the primary interaction of
apoB-100
with factor III is followed by a rate-limiting step that can be accelerated by the presence of either factor X or VII and leads to the inhibition of factor III. Furthermore, a computer-based analysis of the sequences of factor III revealed a possible binding site for
apoB-100
.
...
PMID:The mechanism of inhibition of factor III (thromboplastin) activity by apolipoprotein B-100. Protein-protein interactions. 896 21
Apolipoprotein B-100
acts as an inhibitor of
thromboplastin
activity independently of the tissue factor pathway inhibitor (TFPI) associated with plasma lipoproteins. Analysis of the primary structure of
Apo B-100
showed a higher than expected occurrence of lysine groups in the receptor-binding region. In order to demonstrate the participation of lysine groups of
Apo B-100
in the inhibition of
thromboplastin
,
thromboplastin
and
Apo B-100
were incubated together in the presence of poly-L-lysine, poly-L-arginine, lysine and arginine monomers. The inhibition of
thromboplastin
by
Apo B-100
was completely suppressed in the presence of poly-L-lysine. Poly-L-arginine was found to be less effective and neither lysine or arginine monomers had any significant effect on the inhibitory effect of
Apo B-100
. Alterations in the structure of
Apo B-100
reconstituted in lipid vesicles resembling LDL, brought about by lipid peroxidation and lipid loading were examined by means of Fourier transform infra-red spectroscopy. It was found that, upon oxidation without the addition of cupric ions, the apolipoprotein attains a more exposed conformation with an increase in alpha-helical structure. This increase occurred at the expense of beta-structure. On lipid loading, an increase in beta-structure at the expense of the alpha-helix, was demonstrated. It is therefore proposed that the variable action of LDL towards
thromboplastin
derives from alterations in the secondary structure of the
Apo B-100
, particularly the receptor-binding region.
...
PMID:Alterations in the structure of apolipoprotein B-100 determine the behaviour of LDL towards thromboplastin. 915 Feb 44
