Fluorescein Redirects a Ruthenium−Octaarginine Conjugate to the Nucleus
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.
Copyright © 2009 American Chemical Society. Received March 30, 2009; Publication Date (Web): June 8, 2009. We are grateful to the NIH (GM33309) and to the Caltech Biological Imaging Center.
Accepted Version - nihms123170.pdf
Supplemental Material - Puckettja9025165_si_001.pdf