Abstract: Visualization of Blood Clot Formation Using Restricted Interaction Peptide (RIP) (2011 SACNAS National Conference)

Friday, October 28, 2011

Hall 1-2 (San Jose Convention Center)

Thai Do , Biology, University of California, San Diego, San Diego, CA

Michael Page, PhD , Pharmaceutical Chemistry, University of California, San Francisco, San Francisco

Charles Craik, PhD , Departments of Pharmaceutical Chemistry, Pharmacology, and Biochemistry/Biophysics, University of California, San Francisco, San Francisco, CA

The aim of this study is to examine the capability of the Restricted Interaction Peptide (RIP), Cy3-Protonectin-PAR1, to image and quantify in-vivo thrombin activity. Upon thrombin activation at the cleavage site, the RIP’s membrane interacting region linked to an imaging agent will bind to a phospholipid bilayer producing a high-resolution, non-invasive, real-time image of blood clot formation. Using a bottom-up approach, we observed the properties of the RIP probe through three stages: testing fluorescence at the molecular level, in-vitro staining of murine blood, and in vivo imaging of blood clot in mouse model. We concluded that Cy3-Protonectin-PAR1 has a high selectivity for thrombin with a catalytic efficiency (K_cat/K _m) of 5.3 uM/s and a turnover number (K_cat) of 1.3 s^-1. In addition, a minute sample (~50 nM) of the peptide is capable of producing high resolution blood clot images. Further investigation of the design of RIP is necessary to produce probes that are capable of detecting blood clot in stroke, coronary thrombosis, and pulmonary embolism.