Dina V. Hingorani1, Edward T. Randtke1, Marty Pagel2
1Chemistry and Biochemistry, University of Arizona, Tucson, AZ, United States; 2Biomedical Engineering, University of Arizona, Tucson, AZ, United States
We have characterized the CEST effect of a TGase-responsive PARACEST MRI contrast agent that is conjugated to a protein and hydrophilic peptides that include arginine. The appearance of CEST at -11 ppm differs from the appearance of CEST at +4, +11, and +22 ppm after conjugation of the agent a hydrophobic ZQR peptide, which demonstrates outstanding specificity of CEST for different molecular conformations, which may be exploited to design responsive CEST agents. CEST at -11 ppm before TGase-catalyzed conjugation indicated the formation of a non-covalent supramolecular adduct, which may be further exploited to design responsive CEST agents.