P. Grailhe et al., THE MUTATION IN FIBRINOGEN BICETRE-II (GAMMA-ASN308-]LYS) DOES NOT AFFECT THE BINDING OF T-PA AND PLASMINOGEN TO FIBRIN, Blood coagulation & fibrinolysis, 4(5), 1993, pp. 679-687
The aim of this study was to investigate the interactions of t-PA and
plasminogen with fibrin derived from an abnormal fibrinogen detected i
n a 40-year-old male patient who had had an episode of thrombophlebiti
s with pulmonary embolism. An abnormal fibrinogen was diagnosed on the
basis of prolonged thrombin and reptilase times also detected in two
other family members. Fibrinogen purified from plasma, in the presence
of protease inhibitors, by glycine precipitations, gel filtration and
affinity chromatography, was devoid of plasminogen, fibronectin, and
vWf. SDS-PAGE analysis according to Laemmli under reducing conditions,
showed an abnormal gamma chain (approximately 50% of the total) migra
ting in a more anodic position (M(r) 48 kDa). By PCR amplification and
DNA sequencing, the abnormality was identified as an Asn308-->Lys mut
ation of the gamma chain. Since such a mutation constitutes a new plas
min cleavage site as first reported for fibrinogen Kyoto I, it may mod
ify interactions of plasminogen and t-PA with carboxy-terminal lysine
residues. Ligand-binding studies were therefore performed using intact
and plasmin-degraded fibrin surfaces obtained from the abnormal fibri
nogen. The plasminogen and t-PA binding isotherms obtained with the ab
normal fibrinogen were similar to the control. Moreover, the stimulati
on by fibrin of plasminogen activation by t-PA was not different from
the control. These results suggest (i) that the lysine 308 residue may
not be exposed to plasmin cleavage in fibrin, and (ii) that the throm
botic accident of the propositus cannot be explained by an abnormality
of the plasminogen/t-PA binding to fibrin.