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Oxygen Activation of Apo‐obelin–Coelenterazine Complex
Author(s) -
Eremeeva Elena V.,
Natashin Pavel V.,
Song Lei,
Zhou Yuguang,
van Berkel Willem J. H.,
Liu ZhiJie,
Vysotski Eugene S.
Publication year - 2013
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201300002
Subject(s) - oxygen , chemistry , reactive oxygen species , combinatorial chemistry , photochemistry , biochemistry , organic chemistry
Ca 2+ ‐regulated photoproteins use a noncovalently bound 2‐hydroperoxycoelenterazine ligand to emit light in response to Ca 2+ binding. To better understand the mechanism of formation of active photoprotein from apoprotein, coelenterazine and molecular oxygen, we investigated the spectral properties of the anaerobic apo‐obelin–coelenterazine complex and the kinetics of its conversion into active photoprotein after exposure to air. Our studies suggest that coelenterazine bound within the anaerobic complex might be a mixture of N7‐protonated and C2(−) anionic forms, and that oxygen shifts the equilibrium in favor of the C2(−) anion as a result of peroxy anion formation. Proton removal from N7 and further protonation of peroxy anion and the resulting formation of 2‐hydroperoxycoelenterazine in obelin might occur with the assistance of His175. It is proposed that this conserved His residue might play a key role both in formation of active photoprotein and in Ca 2+ ‐triggering of the bioluminescence reaction.