Protease-Resistant Peptide Ligands Developed from Kalata B1 Scaffold

Strategic Insights -

Researchers from the University of California have successfully developed peptide ligands with high affinity for thrombin, a key enzyme involved in blood clotting, using a library of peptides derived from the kalata B1 scaffold. This scaffold, a cyclic peptide, was chosen for its remarkable stability to proteases, which is essential for therapeutic and diagnostic applications. The researchers employed fluorescence-activated cell sorting to screen a large library of peptides, resulting in the identification of refolded thrombin binders with high nanomolar affinities and slow dissociation rates.

Key Takeaways:

  • A library of over 10^9 variants was constructed by randomizing seven amino acids within a loop of the kalata B1 scaffold.
  • The researchers used fluorescence-activated cell sorting to identify peptide ligands specific for the active site of human thrombin.
  • Refolded thrombin binders exhibited high nanomolar affinities in solution and slow dissociation rates, able to inhibit thrombin's enzymatic activity.
  • The knottin variant mediated 20-fold enhanced affinity for thrombin compared to a single disulfide bond constraint.
  • 80% of a knottin-based thrombin inhibitor remained intact after a 2 h incubation with trypsin and chymotrypsin, demonstrating stability properties.
  • The strategy used in this study may be useful in developing stable peptide ligands for in vivo applications.
  • The researchers from the University of California, led by J.A. Getz, published their study in ACS Chemical Biology in 2011.

Statistics:

  • 10^9 variants: The number of peptides in the library constructed by randomizing seven amino acids within a loop of the kalata B1 scaffold.
  • 2 h: The duration of incubation with trypsin and chymotrypsin, during which 80% of the knottin-based thrombin inhibitor remained intact.
  • 20-fold: The enhanced affinity for thrombin mediated by the knottin variant compared to a single disulfide bond constraint.
  • 80%: The percentage of knottin-based thrombin inhibitor that remained intact after 2 h incubation with trypsin and chymotrypsin.
  • 2011: The year in which the researchers from the University of California published their study in ACS Chemical Biology.

Sources:

  • Serine Endopeptidases
  • J.A. Getz et al., "Protease-Resistant Peptide Ligands from a Knottin Scaffold Library", ACS Chemical Biology, 2011;6(8):837-844.
  • University of California, Institute for Collaborative Biotechnology, Santa Barbara, CA 93106, United States.
  • American Chemical Society, 1155 16th St., NW, Washington, DC 20036, USA.