Abstract: The present invention provides a method of designing an optimized gene which comprises altering a nucleotide sequence of a target protein gene, so that only preferential codons with high frequency of use in human cells are selected and a GC content of not less than 60% is achieved. A gene design method which involves the feature “only preferential codons with high frequency of use are selected and a GC content of not less than 60% is achieved” can be established as a general rule for preparing proteins with high expression level, in order to obtain chemically synthesized genes for proteins capable of high-level expression in eukaryotes.

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 analog 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: The screening method of the present invention is useful for screening drugs such as insulin secretagogues having an insulin secretagogue activity with minimized side effects (hypoglycemia induction, etc.). The transformant in which a polynucleotide encoding the fusion protein used for the screening method is introduced, the screening kit comprising the transformant, etc. are also useful for screening excellent drugs.

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: 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: A novel luciferase that is distinct from conventional luciferase has been desired. A luciferase mutant comprising an amino acid sequence in which glutamic acid at position 4, arginine at position 11, leucine at position 18 and valine at position 27 are substituted with other amino acids, in the amino acid sequence of SEQ ID NO: 2.

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: 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: A simple process for producing ?-coelenterazine compounds has been desired. Described is a process for producing a ?-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 ?-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: A novel luciferase that is distinct from conventional luciferase has been desired. A luciferase mutant comprising an amino acid sequence in which tyrosine at position of 138 is substituted with another amino acid and at least 3 amino acids selected from the group consisting of isoleucine at position of 90, proline at position of 115, glutamine at position of 124 and asparagine at position of 166 are substituted with other amino acids, in the amino acid 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: 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: Secreted luciferases which are different from those known heretofore have been desired. The present invention provides a luciferase mutant comprising an amino acid sequence in which at least one amino acid selected from amino acids at the positions of 1 to 4 is deleted in the amino acid sequence of SEQ ID NO: 2.

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 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 simple process for producing ?-coelenterazine compounds has been desired. The invention provides a process for producing a ?-coelenterazine compound represented by general formula (II) which comprises (1) the step of reacting a compound represented by 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 represented by general formula (X) which is the compound represented by general formula (IX) wherein the amino is protected with R5, and then deprotecting R4 and, if any, R5 to give a ?-coelenteramine compound represented by general formula (XIV), and (3) the step of reacting the compound represented by general formula (XIV) with a compound represented by general formula (XV) to give the compound represented by general formula (II).

Abstract: Luciferases which are different from those known heretofore have been desired. A luciferase mutant comprising an amino acid sequence in which at least one amino acid selected from the group consisting of valine at the position of 44, alanine at the position of 54 and tyrosine at the position of 138 is substituted with other amino acid(s) in the amino acid sequence of SEQ ID NO: 2.

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: 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: 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.