Developing 1,4-Diethyl-1,2,3,4-tetrahydroquinoxalin-substituted Fluorogens Based on GFP Chromophore for Endoplasmic Reticulum and Lysosome Staining.

In the present study, we demonstrated that the introduction of a 1,4-diethyl-1,2,3,4-tetrahydroquinoxalin moiety into the arylidene part of GFP chromophore-derived compounds results in the formation of environment-sensitive fluorogens. The rationally designed and synthesized compounds exhibit remarkable solvent- and pH-dependence in fluorescence intensity. The solvent-dependent variation in fluorescence quantum yield makes it possible to use some of the proposed compounds as polarity sensors suitable for selective endoplasmic reticulum fluorescent labeling in living cells.

A Combination of Library Screening and Rational Mutagenesis Expands the Available Color Palette of the Smallest Fluorogen-Activating Protein Tag nanoFAST.

NanoFAST is the smallest fluorogen-activating protein, consisting of only 98 amino acids, used as a genetically encoded fluorescent tag. Previously, only a single fluorogen with an orange color was revealed for this protein. In the present paper, using rational mutagenesis and in vitro screening of fluorogens libraries, we expanded the color palette of this tag.

Copper coordination compounds with (5,5')-2,2'-(alkane-α,ω-diyldiselenyl)-bis-5-(2-pyridylmethylene)-3,5-dihydro-4-imidazol-4-ones. Comparison with sulfur analogue.

A series of new organic ligands (5,5')-2,2'-(alkane-α,ω-diyldiselenyl)-bis-5-(2-pyridylmethylene)-3,5-dihydro-4-imidazol-4-ones (L) consisting of two 5-(2-pyridylmethylene)-3,5-dihydro-4-imidazol-4-one units linked with polymethylene chains of various lengths ( = 2-10, where is the number of CH units) have been synthesized. The reactions of these ligands with CuCl·2HO and CuClO·6HO gave Cu or Cu containing mono- and binuclear complexes with CuLCl ( = 2-4) or CuL(ClO) ( = 1, 2) composition. It was shown that the agents reducing Cu to Cu in the course of complex formation can be both a ligand and an organic solvent in which the reaction is carried out.

Excited-State Dynamics of a meta-Dimethylamino Locked GFP Chromophore as a Fluorescence Turn-on Water Sensor.

Strategic incorporation of a meta-dimethylamino (-NMe ) group on the conformationally locked green fluorescent protein (GFP) model chromophore (m-NMe -LpHBDI) has drastically altered molecular electronic properties, counterintuitively enhancing fluorescence of only the neutral and cationic chromophores in aqueous solution. A ~200-fold decrease in fluorescence quantum yield of m-NMe -LpHBDI in alcohols (e.g.

NanoFAST: structure-based design of a small fluorogen-activating protein with only 98 amino acids.

One of the essential characteristics of any tag used in bioscience and medical applications is its size. The larger the label, the more it may affect the studied object, and the more it may distort its behavior. In this paper, using NMR spectroscopy and X-ray crystallography, we have studied the structure of fluorogen-activating protein FAST both in the apo form and in complex with the fluorogen.

Color Tuning of Fluorogens for FAST Fluorogen-Activating Protein.

Using benzylidene imidazolone core, we created a panel of color-shifted fluorogenic ligands for FAST protein without compromise to the binding efficiency and the utility for live-cell protein labeling. This study highlights the potential of benzylidene imidazolones derivatives for rapid expansion of a pallet of live-cell fluorogenic labeling tools.