Methods, reagents and kits for luciferase assay
The invention relates to methods, reagents and kits for detecting enzyme activity using bioluminescence. In particular, it relates to a novel luciferase assay system with reduced background luminescence to allow for increased detection sensitivity. Provided is a method of detecting luciferase activity in a sample using coelenterazine or an analog thereof as a substrate, comprising: (a) initiating luciferase-catalyzed luminescence production by contacting said sample with a luciferase detection reagent to yield a reaction mixture, said reagent comprising coelenterazine and at least one iodide source in an amount sufficient to reduce the autoluminescence of said coelenterazine, (b) incubating said reagent mixture under conditions suitable to produce luminescence, and (c) measuring the luminescence produced. Also provided are detections reagents and kits for use in such a method.
1. A method of detecting luciferase activity in a sample using coelenterazine or an analog thereof as a substrate, comprising:
a) preparing a reaction mixture by contacting said sample with coelenterazine or an analog thereof and with at least one iodide source in an amount sufficient to reduce the autoluminescence of said coelenterazine or analog,
b) incubating said reaction mixture under conditions suitable to produce luminescence, and
c) measuring the luminescence produced.
2. The method of claim 1 , wherein said at least one iodide source is an iodide salt.
3. The method of claim 1 , wherein the coelenterazine or analog is selected from the group consisting of native coelenterazine, coelenterazine cp, coelenterazine f, coelenterazine fcp, coelenterazine h, coelenterazine hcp, coelenterazine i, coelenterazine ip and coelenterazine n.
4. The method of claim 1 , wherein the coelenterazine or analog thereof is present in the reaction mixture in a concentration of 2-5 μM.
5. The method of claim 1 , wherein said reaction mixture comprises about 0.02 mM to about 500 mM iodide.
6. The method of claim 2 wherein said iodide salt is selected from the group consisting of NaI, KI, LiI and NH 4 I, or any combination thereof.
7. The method of claim 1 wherein the reaction mixture is a 1-10 mM EDTA buffer solution having a pH between 7.2-8.0.
8. The method of claim 4 wherein the reaction mixture is a 1-10 mM EDTA buffer solution having a pH between 7.2-8.0.