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Abstract #1851

Supercharged Green Fluorescent Proteins as Bimodal Reporter Genes for CEST and Optical Imaging

Amnon Bar-Shir1, 2, Yajie Liang1, 2, Assaf A. Gilad1, 2, Jeff W.M. Bulte1, 2

1Department of Radiology, Johns Hopkins University, Baltimore, MD, United States; 2Institute for Cell Engineering, Johns Hopkins University, Baltimore, MD, United States

Positively charged amino acids (mostly lysine and arginine) in peptide and proteins enable their use as CEST-based contrast agents or reporter genes. We show here that superpositively-charged mutants of the green fluorescent protein (GFP) reporter gene can generate superior CEST contrast. The additional, water-exposed, lysine and arginine amino acids of these mutants were found to increase the CEST contrast obtained from the baseline guanidine (arginine) and amide (lysine and arginine) exchangeable protons. These mutant GFPs retained their fluorescence thus making it a bimodal reporter gene.

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Keywords

absolute achieved acids affinity aggregation amide amino arginine asymmetry audience bimodal boiled capability cell cellular characteristics characterization charge charged chem chromatography clinicians computed contain containing contrast cooled correction correlation derived determined dialyzed display electrophoresis encoding engineering equal especially even examined excellent except exchangeable exposed expressed expression fluorescence fluorescent frequencies frequency gene generate generated genes goal green highly immobilized induction institute invasive johns lysine magic magnetization maps measured media metal modified modify modifying module molecular monitoring mutant mutants natl offsets optical optimized overall page plots previous protein proteins protons pulse pure purified purity radiology rare reporter researchers residues resistant resonant respectively retain retaining reveal rich sample saturation solutions solvent spectra studies supercharged supported target therapy transfer type validated variants water wild