Oxygen Activation of Apo‐obelin–Coelenterazine Complex |
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| Authors: | Dr Elena V Eremeeva Pavel V Natashin Prof Lei Song Prof Yuguang Zhou Prof Willem J H van Berkel Prof Zhi‐Jie Liu Dr Eugene S Vysotski |
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| Affiliation: | 1. National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101 (China);2. Photobiology Laboratory, Institute of Biophysics, Russian Academy of Sciences, Siberian Branch, Akademgorodok 50, Bldg. 50, Krasnoyarsk 660036 (Russia);3. Laboratory of Bioluminescence Biotechnology and Chair of Biophysics, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, Svobodny Ave. 79, Krasnoyarsk 660041 (Russia);4. Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen (The Netherlands);5. China General Microbiological Culture Collection Center, Institute of Microbiology, Chinese Academy of Sciences, 1 Beichen West Road, Beijing 100101 (China);6. Institute of Molecular and Clinical Medicine, Kunming Medical University, 1168 Chun‐Rong Western Road, Kunming 650500 (China) |
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| Abstract: | Ca2+‐regulated photoproteins use a noncovalently bound 2‐hydroperoxycoelenterazine ligand to emit light in response to Ca2+ 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 Ca2+‐triggering of the bioluminescence reaction. |
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| Keywords: | aequorin coelenterazine luminescence photoprotein protein folding |
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