Linear analogues derived from the first EGF-like domain of human blood coagulation factor VII: Enhanced inhibition of FVIIa/TF complex activity by backbone modification through aspartimide formation
M. Husbyn et al., Linear analogues derived from the first EGF-like domain of human blood coagulation factor VII: Enhanced inhibition of FVIIa/TF complex activity by backbone modification through aspartimide formation, J PEPT SCI, 5(7), 1999, pp. 323-329
Coagulation factor VII bound to its cofactor tissue factor is the physiolog
ical initiator of blood coagulation. The interaction between factor VII and
tissue factor involves all four of the structural modules found in factor
VII, with the most significant contribution coming from the first EGF-like
domain. In this study, the synthesis and biological activity of several ana
logues derived from the first EGF-like domain of FVII comprising the sequen
ce 45-83 are reported on. The six cysteine residues found in the native pro
tein were replaced by Abu. The peptides were isolated from a multicomponent
mixture following standard Fmoc solid phase synthesis. Purification and ch
aracterisation of the heterogeneous product showed that aspartimide formati
on was a major side-reaction, occurring predominantly at the Asp(46)-G1y(47
) and Asn(57)-Gly(58) dipeptides. Although relatively common in peptide syn
thesis, the extent to which this side-reaction had taken place was consider
ed surprising. Reported herein are the analytical methods used to isolate a
nd characterise several of the modified products. Also, the inhibitory effe
ct of these peptides on the formation and enzymatic activity of the factor
VIIa/tissue factor complex have been compared. Surprisingly, the peptide co
ntaining an iso-Asp residue at position 57 possessed 66-fold higher inhibit
ory activity compared with the original target peptide. A possible explanat
ion for this increase in observed activity is presented. Copyright (C) 1999
European Peptide Society and John Wiley & Sons, Ltd.