Convenient and efficient synthesis of a lanthanide ³⁺ - Coordinated, diethylene triamine pentaacetic acid labeled biopolymer as an assay for the cholecystokinin B receptor

To develop an assay for the cholecystokinin B receptor with an Eu ³⁺-labeled cholecystokinin peptide via a diethylene triamine pentaacetic acid chelating linker, a commercial dianhydride diethylene triamine pentaacetic acid precursor was directly attached to the N-terminus of cholecystokinin peptides by a solid-phase synthesis method with a satisfactory yield and purity after reverse-phase high-performance liquid chromatography separation. Lanthanide was then coordinated to the peptide via a diethylene triamine pentaacetic acid bifunctional agent. This method is a useful approach to the large-scale synthesis of lanthanide ³⁺-coordinated, diethylene triamine pentaacetic acid labeled biopolymers. This research provides not only a simple and convenient method for the preparation of lanthanide-based peptide ligand libraries but also possible lanthanide-based highthroughput screening of peptide receptors with a timeresolved fluorescence assay system. Five biopolymers were synthesized and characterized with high-resolution electrospray ionization in this study.