Enzyme Catalyzed Site-specific Protein Labeling And Cell Imaging With Quantum Dots

摘要

We have developed an efficient method for one-step covalent labeling of cell surface proteins with quantum dots based on enzyme catalyzed site-specific modification of short peptide tags.rnQuantum dots (QDs) have recently emerged as powerful fluorescent probes for biological imaging due to their superior optical properties such as high quantum yields, excellent photostability, size-tunable emission spectra and multiplex excitation at a single wavelength. Biologically compatible QDs have been prepared for cell imaging applications by coating the QD surface with amphi-philic polymers, phospholipids and small molecules. QD coatings can be further functionalized with protein ligands or antibodies to label specific cellular proteins. Recently streptavidin-conjugated QDs have been used to label cell surface proteins. This method requires the target proteins to be first labeled with biotin by constructing fusions of the target proteins with a short peptide tag (AP tag) or with an acyl carrier protein (ACP) tag for biotin attachment catalyzed by biotin ligase or phosphopantetheinyl transferase5 respectively (Fig. la).