Tetramerization of peptides results in high-affinity binding.

Competition studies of synthetic peptides with TM11-PO (2 nM) for P-selectin binding were performed in an ELISA. (A) Competition of TM11 (▪) with TM11-PO resulted in an IC₅₀ of 2 μM. A 200-fold increase in affinity was observed when TM11 was presented as a tetramer, (TM11)₄, by conjugation of TM11-biotin to streptavidin (▴, IC₅₀ = 10 nM). (B) The IC₅₀ of monomeric TM31 (▪, 19 μM) was 300-fold lower than that of tetrameric TM31 (▴, IC₅₀ = 61 nM). Values represent means of triplicate experiments ± variation.