High Field MR Imaging of Proteins and Peptides Based on the Amine-Water Proton Exchange Effect

Tao Jin¹, Seong-Gi Kim¹

The amide proton transfer (APT) effect is sensitive to the mobile protein/peptide levels but its imaging contrast in vivo is quite low because the amide water exchange is very slow. Recently, it has been proposed that a novel chemical exchange contrast based on the faster amine-water proton exchange (APEX) may also be sensitive to protein/peptide concentrations. Here we measured labile amide, amine and hydroxyl protons at 9.4 T using different protein and peptide phantoms and showed that the APEX contrast may potentially be a more sensitive biomarker than APT for protein/peptide imaging at a high magnetic field.