Supporting Information Split Ligand for Lanthanide Binding: Facile Evaluation of Dimerizing Proteins

I. General methods All Fmoc-protected natural amino acids were purchased from Advanced Chemtech (Louisville, KY). Fmocperfluorophenylalanine (Fmoc-Z) was purchased from Chem-Impex Int’l Inc.(Wood Dale, IL). Fmoc-Gly-Wang resin was purchased from Novabiochem (San Diego, CA). All other chemicals were purchased from Sigma-Aldrich (Milwaukee, WI). Peptide synthesis was finished on a Tribute peptide synthesizer (Protein Technologies, Tucson, AZ). H-NMR and C-NMR data were collected on a Varian Gemini 500 MHz NMR spectrometer. HR-MS data were generated by Boston College Mass-Spec facilities. The concentration of all labeled proteins was determined in Tris buffer (10 mM Tris, 100 mM Sodium Citrate, pH=8.5) by measuring their absorption at 350 nm (ε = 13,405 M cm) on a Thermo Scientific NanoDrop 2000c (Wilmington, DE). All fluorescence data were collected on a Fluorolog spectrometer (Horiba Jobin Yvon FL3-22).