title: Synthesis and characterization of a small, membrane-permeant, caspase-activatable far-red fluorescent peptide for imaging apoptosis.
abstract: To image apoptosis in vivo with a small, membrane-permeant probe, TcapQ(647) was synthesized comprising a Tat-peptide-based permeation peptide sequence, an effector caspase recognition sequence, DEVD, and a flanking optically activatable pair comprising a far-red quencher, QSY 21, and a fluorophore, Alexa Fluor 647. Under baseline conditions, high quenching efficiencies were observed resulting in low background fluorescence. Upon exposure to executioner caspases, TcapQ(647) was specifically cleaved, thereby releasing the fluorophore from the quencher and enabling imaging of apoptosis.
authors.affiliation: Molecular Imaging Center, Mallinckrodt Institute of Radiology, St. Louis, Missouri 63110, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Bullok
authors.forename: David
authors.initials: D
authors.lastname: Piwnica-Worms
mesh_terms: D017209:Apoptosis; D020169:Caspases / Q000737:chemistry / Q000378:metabolism*; D002463:Cell Membrane Permeability; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D019169:Jurkat Cells; D007624:KB Cells; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics
chemical_list: D005456:Fluorescent Dyes; D009842:Oligopeptides; D010455:Peptides; C519706:TcapQ647 peptide; D020169:Caspases