Abstract: A complementation system including two fragments of photoactive yellow protein (PYP), or truncated fragments thereof, and its use with a fluorogenic hydroxybenzylidene rhodanine (HBR) analog for detecting interactions between biological molecules of interest, in particular between proteins of interest. Especially, a complementation system including a first PYP fragment having an amino acid sequence having at least about 70% identity with the amino acid sequence of SEQ ID NO: 23, or a truncated fragment thereof including at least 89 consecutive amino acids from the C-terminal end of the amino acid sequence; and a second PYP fragment having an amino acid sequence having at least about 70% identity with the amino acid sequence of SEQ ID NO: 34, or a truncated fragment thereof including at least 8 consecutive amino acids of the amino acid sequence, preferably 8 consecutive amino acids from the N-terminal end of the amino acid sequence.

Abstract: Fluorescent labeling of proteins. In particular, membrane-impermeant fluorogenic chromophores being capable of binding reversibly a functional derivative of a Photoactive Yellow Protein (PYP), or a functional fragment thereof, for fluorescently labeling biological molecules of interest, preferably proteins of interest. Especially, 4-hydroxybenzylidene-rhodanine (HBR) analogs of formula (II) as membrane-impermeant fluorogenic chromophores.

Abstract: Fluorescent labeling of proteins. In particular, membrane-impermeant fluorogenic chromophores being capable of binding reversibly a functional derivative of a Photoactive Yellow Protein (PYP), or a functional fragment thereof, for fluorescently labeling biological molecules of interest, preferably proteins of interest. Especially, 4-hydroxybenzylidene-rhodanine (HBR) analogs of formula (II) as membrane-impermeant fluorogenic chromophores.

Abstract: A method for detection of at least one reversibly photo-convertible fluorescent species, comprises the following steps: a) illumination of a sample comprising said or at least one of the reversibly photo-convertible fluorescent species by a periodically modulated illuminating light; and b) detection of fluorescent emission emitted by the sample thus illuminated; wherein the method further comprises the following step: c) extraction of the amplitude of the intensity component of the fluorescent emission exhibiting the same periodicity as the periodically modulated illuminating light and a phase quadrature with respect to the same; and wherein the mean intensity of the illuminating light and the modulation frequency of the same are chosen to maximize the amplitude of the intensity component of the fluorescent emission.

Abstract: Disclosed is a functional derivative of a Photoactive Yellow Protein (PYP), or a functional fragment thereof, for fluorescently labelling particles, e.g. proteins, or surfaces, which is capable of binding reversibly a fluorogenic chromophore of formula (I), and which is capable of enhancing the brightness of the fluorogenic chromophore upon complexation thereto; and of inducing the spectral shift of the fluorogenic chromophore through the ionization of an auxochromic group thereof.

Abstract: Disclosed is a functional derivative of a Photoactive Yellow Protein (PYP), or a functional fragment thereof, for fluorescently labelling particles, e.g. proteins, or surfaces, which is capable of binding reversibly a fluorogenic chromophore of formula (I), and which is capable of enhancing the brightness of the fluorogenic chromophore upon complexation thereto; and of inducing the spectral shift of the fluorogenic chromophore through the ionization of an auxochromic group thereof.

Abstract: Method for detection of at least one reversibly photo-convertible fluorescent species (P), comprising the following steps: a) illumination of a sample comprising said or at least one of said reversibly photo-convertible fluorescent species by a periodically modulated illuminating light (FEX); and b) detection of fluorescent emission (FLU) emitted by the sample thus illuminated; characterized in that the method further comprises the following step: c) extraction of the amplitude (IFOUt) of the intensity component of said fluorescent emission exhibiting the same periodicity as said periodically modulated illuminating light and a phase quadrature with respect to the same; and in that the mean intensity of said illuminating light and the modulation frequency of the same are chosen in such a way as to maximise said amplitude of the intensity component of said fluorescent emission.

Abstract: The invention relates to new proteins called alkylcytosine transferases (ACTs) derived from O6-alkylguanine-DNA alkyltransferase, and to substrates for ACTs specifically transferring a label to these ACTs and to fusion proteins comprising these. The substrates according of the invention are substituted cytosines of formula (I) wherein R1 is an aromatic or a heteroaromatic group, or an optionally substituted unsaturated alkyl, cycloalkyl or heterocyclyl group with the double bond connected to OCH2—; R2 is a linker; and L is a label or a plurality of same or different labels. The invention further relates to methods of transferring label L from these substrates of formula (I) to ACTs and ACT fusion proteins. The system of ACT-compound of formula (I) is particularly suitable for double labelling studies together with the known system O6-alkylguanine-DNA alkyltransferase (AGT)-benzylguanines.

Abstract: The invention relates to a caged lysine, wherein the caged lysine is according to Formula (I): or salts thereof. The invention further relates to polypeptides comprising a caged lysine, and to methods of making same. The invention further relates to tRNA synthetases capable of charging tRNA with caged lysine.

Abstract: The invention relates to new proteins called alkylcytosine transferases (ACTs) derived from O6-alkylguanine-DNA alkyltransferase, and to substrates for ACTs specifically transferring a label to these ACTs and to fusion proteins comprising these. The substrates according of the invention are substituted cytosines of formula (I) wherein R1 is an aromatic or a heteroaromatic group, or an optionally substituted unsaturated alkyl, cycloalkyl or heterocyclyl group with the double bond connected to OCH2—; R2 is a linker; and L is a label or a plurality of same or different labels. The invention further relates to methods of transferring label L from these substrates of formula (I) to ACTs and ACT fusion proteins. The system of ACT-compound of formula (I) is particularly suitable for double labelling studies together with the known system O6-alkylguanine-DNA alkyltransferase (AGT)-benzylguanines.

Abstract: The invention relates to new proteins called alkylcytosine transferases (ACTs) derived from O6-alkylguanine-DNA alkyltransferase, and to substrates for ACTs specifically transferring a label to these ACTs and to fusion proteins comprising these. The substrates according of the invention are substituted cytosines of formula (I) wherein R1 is an aromatic or a heteroaromatic group, or an optionally substituted unsaturated alkyl, cycloalkyl or heterocyclyl group with the double bond connected to OCH2—; R2 is a linker; and L is a label or a plurality of same or different labels. The invention further relates to methods of transferring label L from these substrates of formula (I) to ACTs and ACT fusion proteins. The system of ACT-compound of formula (I) is particularly suitable for double labelling studies together with the known system O6-alkylguanine-DNA alkyltransferase (AGT)-benzylguanines.

Abstract: The invention relates to new proteins called alkylcytosine transferases (ACTs) derived from O6-alkylguanine-DNA alkyltransferase, and to substrates for ACTs specifically transferring a label to these ACTs and to fusion proteins comprising these. The substrates according of the invention are substituted cytosines of formula (I) wherein R1 is an aromatic or a heteroaromatic group, or an optionally substituted unsaturated alkyl, cycloalkyl or heterocyclyl group with the double bond connected to OCH2—; R2 is a linker; and L is a label or a plurality of same or different labels. The invention further relates to methods of transferring label L from these substrates of formula (I) to ACTs and ACT fusion proteins. The system of ACT-compound of formula (I) is particularly suitable for double labelling studies together with the known system O6-alkylguanine-DNA alkyltransferase (AGT)-benzylguanines.