The lipid phosphatidylserine (PS) is exclusively localized in the inner leaflet of the plasma membrane of healthy cells. The externalization of PS to the outer leaflet is a flag event of apoptosis. Surface presentation of PS was also recently reported for endothelial cells of tumor vasculature. Therefore specific targeting of PS may yield novel technologies for tumor imaging and drug delivery. Previous PS-targeting agents often require metal cations (e.g. Ca2+ or Zn2+) as co-factors and bind PS through electrostatic forces. Herein we report a cyclic peptide scaffold (cLac) that recognizes PS without the need of metal cofactors. The cyclic peptide is designed to mimic the PS-binding protein, lactadherin. Characterization and optimization of this unique PS-targeting agent will be presented. The utilization of cLac in imaging cell apoptosis will be also discussed.

Cofactor free detection of phosphatidylserine with rationally designed cyclic peptides

244th National Meeting (2012)

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