An undecapeptide (residues 106-116 of cow
kappa-casein) is known to inhibit human platelet aggregation and
fibrinogen binding through inhibition of the interaction between the
fibrinogen gamma-chain C-terminus and alphaIIbbeta3. This was due to structural homologies with the
fibrinogen gamma-chain C-terminal dodecapeptide. We have therefore compared in this work the in vitro anti-aggregating activity of
kappa-casein split
peptides and their in vivo potential antithrombotic activity in a model of arterial
thrombosis triggered by
laser-induced intimal injury in the guinea-pig. Caseinoglycopeptide (residues 106-169), the undecapeptide (residues 106-116) and the pentapeptide KNQDK (residues 112-116) from cow
kappa-casein, were anti-aggregating
peptides and exerted a significant antithrombotic activity in the guinea-pig. Caseinoglycopeptides from three species (cow, ewe and human) were also antithrombotic and the most potent being the human one. The antithrombotic activity was achieved in vivo for doses less than the one suspected from in vitro data and for which, ex vivo platelet aggregation was not decreased. In conclusion, the relative involvement of the
fibrinogen gamma-chain C-terminal dodecapeptide could be much more important in in vivo
thrombosis process than in in vitro platelet aggregation. Its specificity and activity in vivo unveiled an interesting potential way for inhibition of arterial
thrombosis if alternative molecular presentation (i.e.
peptidomimetics) and alternative route (i.e. per os) can be developed.