A Novel Class of Small Functional Peptides that Bind and Inhibit Human α-Thrombin Isolated by mRNA Display Original Research Article

Here we report the in vitro selection of novel small peptide motifs that bind to human α-thrombin. We have applied mRNA display to select for thrombin binding peptides from an unbiased library of 1.2 × 1011 different 35-mer peptides, each containing a random sequence of 15 amino acids. Two clones showed binding affinities ranging from 166 to 520 nM. A conserved motif of four amino acids, DPGR, was identified. Clot formation of human plasma is inhibited by the selected clones, and they downregulate the thrombin-meditated activation of protein C. The identified peptide motifs do not share primary sequence similarities to any of the known natural thrombin binding motifs. As new inhibitors for human thrombin open interesting possibilities in thrombosis research, our newly identified peptides may provide further insights into this field of investigation and may be possible candidates for the development of new anti-thrombotic agents.