title: Dual-fluorescence pH probe for bio-labelling.
abstract: Although seminaphtorhodafluor (SNARF) dyes are already widely used to measure pH in cells and at biofilms, their synthesis has low yield and results in an unspecific position of a carboxy-group. The separation of 5'- and 6'-carboxy-SNARF reveals a pKa difference of 0.15, calling into question pH measurements with the (commercially available) mixture. Here we replace the bulky external dicarboxyphenyl ring with a propionate group and evaluate the spectral properties of the new derivative. Proceeding to the ethyl-iodoacetamide, covalent linkage to cysteine protein sites is achieved efficiently as shown with a cyanobacterial phytochrome, extending the scarce application of SNARF in bio-labelling in the current literature. Application in fluorescence lifetime imaging is demonstrated both with the lifetime-based and ratiometric-yield method.
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, 12489 Berlin, Germany. nernst@chemie.hu-berlin.de.
authors.forename: C
authors.initials: C
authors.lastname: Richter
authors.affiliation: Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany. ulrike.alexiev@fu-berlin.de.
authors.forename: C
authors.initials: C
authors.lastname: Schneider
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, 12489 Berlin, Germany. nernst@chemie.hu-berlin.de.
authors.forename: M T
authors.initials: MT
authors.lastname: Quick
authors.affiliation: Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany. ulrike.alexiev@fu-berlin.de.
authors.forename: P
authors.initials: P
authors.lastname: Volz
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, 12489 Berlin, Germany. nernst@chemie.hu-berlin.de.
authors.forename: R
authors.initials: R
authors.lastname: Mahrwald
authors.affiliation: Institute for Plantphysiology, Justus-Liebig Universität, 35390 Giessen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Hughes
authors.affiliation: Institute for Physical and Theoretical Chemistry, Universität Regensburg, 93053 Regensburg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Dick
authors.affiliation: Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany. ulrike.alexiev@fu-berlin.de.
authors.forename: U
authors.initials: U
authors.lastname: Alexiev
authors.affiliation: Department of Chemistry, Humboldt-Universität zu Berlin, 12489 Berlin, Germany. nernst@chemie.hu-berlin.de.
authors.forename: N P
authors.initials: NP
authors.lastname: Ernsting
mesh_terms: D000588:Amines / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry*; D003998:Dicarboxylic Acids / Q000737:chemistry; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D020283:Photoreceptors, Microbial; D010834:Phytochrome / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry; D011494:Protein Kinases / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D000588:Amines; D001426:Bacterial Proteins; D003998:Dicarboxylic Acids; D005456:Fluorescent Dyes; D020283:Photoreceptors, Microbial; D011422:Propionates; D010834:Phytochrome; D011494:Protein Kinases; C413623:Cph1 phytochrome protein, bacteria