Abstract: The invention provides calcium-binding photoproteins which can detect light emission with a higher sensitivity. The proteins of the invention comprising the amino acid sequence of SEQ ID NO: 2 can be used for the detection and measurement of calcium ions. The proteins of the invention are useful as reporter proteins, luminescent markers, etc. The polynucleotides of the invention are useful as reporter genes, etc.

Abstract: A process for producing coelenteramide or its analog in a high yield has been desired. The invention provides a process for producing di-O-methylcoelenteramide or its analog of formula (3) which comprises reacting O-methylcoelenteramine or its analog with 4-methoxyphenylacetyl halide or its analog. The invention also provides a process for producing coelenteramide or its analog, which comprises demethylation of di-O-methylcoelenteramide or its analog.

Abstract: Coelenterazine analogs with different luminescence properties from conventional ones and coelenteramide analogs with different fluorescence properties from conventional ones have been desired. The invention provides coelenterazine analogs modified at the 8-position of coelenterazine and coelenteramide analogs modified at the 2- or 3-position of coelenteramide.

Abstract: Coelenterazine analogs having luminescence properties different from those of known coelenterazine analogs are desired for various luciferases. The invention provides compounds represented by general formula (1) below.

Abstract: A target protein is prepared as soluble protein using a recombinant protein expression system. An expression vector is used that includes (1) an expression-inducible promoter sequence; (2) a first coding sequence including a polynucleotide coding for a polypeptide that is represented by the formula (Z)n; and (3) a second coding sequence that includes a polynucleotide that codes for a target protein. A method of producing the target protein is also used that includes expressing protein using this expression vector.

Abstract: There has been a need for coelenterazine analogs that exhibit luminescence properties different from those of known coelenterazine analogs. The present invention provides the compound represented by general formula (1).

Abstract: There has been a demand for a codon-optimized gene for the mutated catalytic domain of Oplophorus luciferase, which is capable of efficiently expressing a protein both in a cultured animal cell and Escherichia coli. There has also been a demand for a substrate coelenterazine analogue showing a higher activity than that of native 19 kDa protein. The invention provides a polynucleotide comprising a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 2. According to the invention, bis-coelenterazine is used as a substrate coelenterazine analogue suitable for the photoprotein encoded by the polynucleotide comprising the polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 2.

Abstract: Calcium-binding photoproteins showing the luminescence pattern with a slow decay of are desired. The invention provides a mutant apoprotein comprising an amino acid sequence wherein the 23rd to 34th amino acids in the amino acid sequence of SEQ ID NO: 2 are substituted with an amino acid represented by formula I below: Xaa23-Xaa24-Xaa25-Xaa26-Xaa27-Xaa28-Xaa29-Xaa30-Xaa31-Xaa32-Xaa33-Xaa 34; having a function to bind to the peroxide of coelenterazine or the peroxide of a coelenterazine analogue to form a photoprotein capable of emitting light under the action of calcium ions; and, having a half decay time of the luminescence emitted by binding of the photoprotein to calcium ions being not less than 2 seconds.

Abstract: A simple process for producing v-coelenterazine compounds has been desired. Described is a process for producing a v-coelenterazine compound represented by general formula (II) comprising (1) the step of reacting a compound of general formula (VIII) with a methyltriphenylphosphonium salt in the presence of a base to give a compound represented by general formula (IX), (2) the step of performing a ring-closing metathesis reaction on any one selected from the group consisting of the compound represented by general formula (IX) and a compound of general formula (X) which is the compound of general formula (IX) wherein the amino is protected with R5, and then deprotecting R4 and, if any, R5 to give a v-coelenteramine compound represented by general formula (XIV), and (3) the step of reacting the compound of general formula (XIV) with a compound represented by general formula (XV) to give the compound of general formula (II).

Abstract: The invention provides calcium-binding photoproteins which can detect light emission with a higher sensitivity. The proteins of the invention comprising the amino acid sequence of SEQ ID NO: 2 can be used for the detection and measurement of calcium ions. The proteins of the invention are useful as reporter proteins, luminescent markers, etc. The polynucleotides of the invention are useful as reporter genes, etc.

Abstract: A simple process for producing v-coelenterazine compounds has been desired. Described is a process for producing a v-coelenterazine compound represented by general formula (II) comprising (1) the step of reacting a compound of general formula (VIII) with a methyltriphenylphosphonium salt in the presence of a base to give a compound represented by general formula (IX), (2) the step of performing a ring-closing metathesis reaction on any one selected from the group consisting of the compound represented by general formula (IX) and a compound of general formula (X) which is the compound of general formula (IX) wherein the amino is protected with R5, and then deprotecting R4 and, if any, R5 to give a v-coelenteramine compound represented by general formula (XIV), and (3) the step of reacting the compound of general formula (XIV) with a compound represented by general formula (XV) to give the compound of general formula (II).

Abstract: There has been a need for coelenterazine analogs that exhibit luminescence properties different from those of known coelenterazine analogs. The present invention provides the compound represented by general formula (1).

Abstract: Coelenterazine analogues with different luminescence properties from conventional ones and coelenteramide analogues with different fluorescence properties from conventional ones have been desired. The invention provides coelenterazine analogues modified at the 8-position of coelenterazine and coelenteramide analogues modified at the 2- or 3-position of coelenteramide.

Abstract: A fluorescent protein (bFP) having chemiluminescence activity is a complex composed of the apoprotein of a calcium-binding photoprotein, coelenteramid or an analog thereof, and calcium ions or divalent or trivalent ions that can be substituted for the calcium ions. In the complex, the ratio of the number of molecules of the apoprotein to that of the coelenteramid is 1:1 and the ratio of the number of molecules of the apoprotein to that of the divalent or trivalent ions is 1:1 to 1:4. The fluorescent protein is used as a marker because it catalyzes luminescence of coelenterazine and has fluorescence capability. Removal of calcium ions etc. from this fluorescent protein (bFP) having luminescence activity provides a novel fluorescent protein (gFP). Mixing this gFP with the coelenterazine provides a calcium-binding photoprotein, which emit light instantaneously, enabling use as a marker.

Abstract: An excellent protein stabilizer is provided, which has the following effects: (1) low probability with contamination of pathogens, (2) the effect of stabilization on photoproteins, and (3) minimization of loss of activity under lyophilizing conditions. A peptide from fish is used as the active ingredient for the protein stabilizer.

Abstract: Coelenterazine analogues with different luminescence properties from conventional ones and coelenteramide analogues with different fluorescence properties from conventional ones have been desired. The invention provides coelenterazine analogues modified at the 8-position of coelenterazine and coelenteramide analogues modified at the 2- or 3-position of coelenteramide.

Abstract: There has been a need for coelenterazine analogs that exhibit luminescence properties different from those of known coelenterazine analogs. The present invention provides the compound represented by general formula (1).

Abstract: The fusion protein comprising (1) a first region comprising the amino acid sequence of SEQ ID NO: 18 and (2) a second region comprising an amino acid sequence for a polypeptide containing at least one cysteine residue for binding to other useful compound via the thiol group can be modified by chemical modification, and thus has a high catalytic ability for a luminescence activity and is highly available for general purposes.

Abstract: A process for producing coelenteramide or its analog in a high yield has been desired. The invention provides a process for producing di-O-methylcoelenteramide or its analog of formula (3) which comprises reacting O-methylcoelenteramine or its analog with 4-methoxyphenylacetyl halide or its analog. The invention also provides a process for producing coelenteramide or its analog, which comprises demethylation of di-O-methylcoelenteramide or its analog.

Abstract: A protein according to the invention can be used to detect or measure calcium ions is provided. Further the protein is useful as a reporter protein or a luminescence marker. A polynucleotide according to the invention is also useful as a reporter gene.