title: A self-immolative reporter for beta-galactosidase sensing.
abstract: A dual fluorogenic and chromogenic probe, Gal-2SBPO, has been developed based on a synthesized water-soluble dye, 9-di-3-sulfonyl-propylaminobenzo[a]phenoxazonium perchloride (2SPBO, lambda(ex/em)=630/670 nm). beta-D-Galactopyranoside, the substrate of beta-galactosidase, was conjugated to 2SBPO through a para-substituted benzyloxycarbonyl group and a glycine residue, which serve as a self-immolative spacer and as a molecular blocker to mask the optical signal of 2SBPO, respectively. Gal-2SBPO was soluble and stable under physiological conditions. Enzymatic cleavage of the beta-D-galactopyranoside triggered a series of spontaneous reactions that resulted in a release of optically active 2SBPO. The beta-galactosidase activity was assayed by monitoring the absorbance at 630 nm and fluorescence at 670 nm.
authors.affiliation: Center of Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Room 5406, Charlestown, MA 02129, USA.
authors.forename: Nan-Hui
authors.initials: NH
authors.lastname: Ho
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
authors.forename: Ching-Hsuan
authors.initials: CH
authors.lastname: Tung
mesh_terms: D002241:Carbohydrates / Q000737:chemistry; D004798:Enzymes / Q000737:chemistry; D005690:Galactose / Q000737:chemistry; D005697:Galactosides / Q000737:chemistry; D005966:Glucuronidase / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008856:Microscopy, Fluorescence / Q000295:instrumentation*; D008956:Models, Chemical; D013997:Time Factors; D014867:Water / Q000737:chemistry; D001616:beta-Galactosidase / Q000737:chemistry*; D001617:beta-Glucosidase / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D004798:Enzymes; D005697:Galactosides; D014867:Water; D001617:beta-Glucosidase; D001616:beta-Galactosidase; D005966:Glucuronidase; D005998:Glycine; D005690:Galactose