title: Target-activated coumarin phototriggers specifically switch on fluorescence and photocleavage upon bonding to thiol-bearing protein.
abstract: A new concept in which only the molecular target, such as a thiol-bearing protein, can activate the phototrigger has been demonstrated. Such target-activatable phototriggers comprise three parts: a 7-aminocoumarin phototrigger, an electron acceptor (maleimide) that efficiently quenches the coumarin excited state, and a caged leaving group attached to the coumarin. In the absence of mercaptans, photoinduced electron transfer between coumarin and maleimide effectively blocks both the fluorescence and photocleavage pathways. Thiol-bearing molecules, however, readily annihilate the electron acceptor and thus restore the phototrigger for photorelease of the caged cargo (e.g., biotin). Unlike traditional phototriggers, functional-group-activated phototriggers allow easy handling under ambient light, report specific bonding to the target, and enable photocleavage capability selectively at the binding site in situ, thus effectively positioning the photoreleased cargo at the target. Meanwhile, the unique feature of thiol-specific activation of the fluorescence and photocleavage make our new phototrigger a universal tool that can be used to identify accurately protein cysteine S-nitrosylation, a physiologically important posttranslational modification.
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, PR China.
authors.forename: Qiuning
authors.initials: Q
authors.lastname: Lin
authors.forename: Chunyan
authors.initials: C
authors.lastname: Bao
authors.forename: Shuiyu
authors.initials: S
authors.lastname: Cheng
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
authors.forename: Linyong
authors.initials: L
authors.lastname: Zhu
mesh_terms: D003374:Coumarins / Q000737:chemistry*; D005453:Fluorescence; D008301:Maleimides / Q000737:chemistry; D010777:Photochemistry; D010782:Photolysis; D011506:Proteins / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D003374:Coumarins; D008301:Maleimides; D011506:Proteins; D013438:Sulfhydryl Compounds; C043592:maleimide; C080488:7-aminocoumarin