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:3.4.21.5 (
thrombin
)
33,306
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The complement system is an important recognition and effector mechanism of the innate immune system that upon activation leads to the elimination of foreign bodies. It can be activated through three pathways of which the lectin pathway is one. The lectin pathway relies on the binding of mannan-binding lectin (MBL) or the ficolins and the subsequent activation of the MBL-associated serine proteases (MASPs), namely,
MASP1
, 2 and 3 which all form complexes with both MBL and the ficolins. Major substrates have only been identified for MASP2 i.e. C4 and C2. For
MASP1
only a few protein substrates which are cleaved at a low rate have been identified while none are known for MASP3. Since chromogenic substrate screenings have shown that
MASP1
has
thrombin
-like activity, we wanted to investigate the catalytic potential of
MASP1
towards two major proteins involved in the clotting process, fibrinogen and factor XIII, and compare the activity directly with that of
thrombin
. We found that rMASP1 and
thrombin
cleave factor XIII A-chain and the fibrinogen beta-chain at identical sites, but differ in cleavage of the fibrinogen alpha-chain. The
thrombin
turnover rate of factor XIII is approximately 650 times faster than that of rMASP1 at 37 degrees C, pH 7.4. rMASP1 cleavage of fibrinogen leads to the release of the proinflammatory peptide fibrinopeptide B. Thus rMASP1 has similar, but not identical specificity to
thrombin
and its catalytic activity for factor XIII and fibrinogen cleavage is much lower than that of
thrombin
. Nevertheless, rMASP1 can drive the formation of cross-linked fibrinogen. Since
MASP1
is activated on contact of MBL or the ficolins with microorganisms, fibrinogen and factor XIII may be involved in the elimination of invading pathogens.
...
PMID:The action of MBL-associated serine protease 1 (MASP1) on factor XIII and fibrinogen. 1845 10
