Reaction: coelenterazine h + O2 = excited coelenteramide h monoanion + CO2 (over-all reaction)
(1a) coelenterazine h + O2 = coelenterazine h dioxetanone
(1b) coelenterazine h dioxetanone = excited coelenteramide h monoanion + CO2
For diagram of reaction, click here
Glossary: coelenterazine h = Renilla luciferin = 2,8-dibenzyl-6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one
coelenteramide h = Renilla oxyluciferin = N-[3-benzyl-5-(4-hydroxyphenyl)pyrazin-2-yl]-2-phenylacetamide
Other name(s): Renilla-luciferin 2-monooxygenase; luciferase (Renilla luciferin); Renilla-luciferin:oxygen 2-oxidoreductase (decarboxylating)
Systematic name: coelenterazine h:oxygen 2-oxidoreductase (decarboxylating)
Comments: This enzyme has been studied from the soft coral Renilla reniformis. Before the reaction occurs the substrate is sequestered by a coelenterazine-binding protein. Elevation in the concentration of calcium ions releases the substrate, which then interacts with the luciferase. Upon binding the substrate, the enzyme catalyses an oxygenation, producing a very short-lived hydroperoxide that cyclizes into a dioxetanone structure, which collapses, releasing a CO2 molecule. The spontaneous breakdown of the dioxetanone releases the energy (about 50 kcal/mole) that is necessary to generate the excited state of the coelenteramide product, which is the singlet form of the monoanion. In vivo the product undergoes the process of nonradiative energy transfer to an accessory protein, a green fluorescent protein (GFP), which results in green bioluminescence. In vitro, in the absence of GFP, the product emits blue light.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 61869-41-8
References:
1. Cormier, M.J., Hori, K. and Anderson, J.M. Bioluminescence in coelenterates. Biochim. Biophys. Acta 346 (1974) 137-164. [PMID: 4154104]
2. Hori, K., Anderson, J.M., Ward, W.W. and Cormier, M.J. Renilla luciferin as the substrate for calcium induced photoprotein bioluminescence. Assignment of luciferin tautomers in aequorin and mnemiopsin. Biochemistry 14 (1975) 2371-2376. [PMID: 237531]
3. Anderson, J.M., Charbonneau, H. and Cormier, M.J. Mechanism of calcium induction of Renilla bioluminescence. Involvement of a calcium-triggered luciferin binding protein. Biochemistry 13 (1974) 1195-1200. [PMID: 4149963]
4. Shimomura, O. and Johnson, F.H. Chemical nature of bioluminescence systems in coelenterates. Proc. Natl. Acad. Sci. USA 72 (1975) 1546-1549. [PMID: 236561]
5. Charbonneau, H. and Cormier, M.J. Ca2+-induced bioluminescence in Renilla reniformis. Purification and characterization of a calcium-triggered luciferin-binding protein. J. Biol. Chem. 254 (1979) 769-780. [PMID: 33174]
6. Lorenz, W.W., McCann, R.O., Longiaru, M. and Cormier, M.J. Isolation and expression of a cDNA encoding Renilla reniformis luciferase. Proc. Natl. Acad. Sci. USA 88 (1991) 4438-4442. [PMID: 1674607]
7. Loening, A.M., Fenn, T.D. and Gambhir, S.S. Crystal structures of the luciferase and green fluorescent protein from Renilla reniformis. J. Mol. Biol. 374 (2007) 1017-1028. [PMID: 17980388]