title: Fluorescein redirects a ruthenium-octaarginine conjugate to the nucleus.
abstract: The cellular uptake and localization of a Ru-octaarginine conjugate with and without an appended fluorescein are compared. The inherent luminescence of the Ru(II) dipyridophenazine complex allows observation of its uptake without the addition of a fluorophore. Ru-octaarginine-fluorescein stains the cytosol, nuclei, and nucleoli of HeLa cells under conditions where the Ru-octaarginine conjugate without fluorescein shows only punctate cytoplasmic labeling. At higher concentrations, however, Ru-octaarginine without the fluorescein tag does exhibit cytoplasmic, nuclear, and nucleolar staining. Attaching fluorescein to Ru-octaarginine lowers the threshold concentration required for diffuse cytoplasmic labeling and nuclear entry. Hence, the localization of the fluorophore-bound peptide cannot serve as a proxy for that of the free peptide.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Cindy A
authors.initials: CA
authors.lastname: Puckett
authors.forename: Jacqueline K
authors.initials: JK
authors.lastname: Barton
mesh_terms: D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D019793:Fluorescein / Q000032:analysis / Q000737:chemistry* / Q000493:pharmacokinetics*; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D008163:Luminescent Measurements; D009842:Oligopeptides / Q000032:analysis / Q000737:chemistry / Q000493:pharmacokinetics*; D010539:Permeability; D012428:Ruthenium / Q000032:analysis / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: D009842:Oligopeptides; C448619:octaarginine; D012428:Ruthenium; D019793:Fluorescein