Spectral components of bioluminescence of aequorin and obelin

Complex bioluminescence spectra of photoproteins from marine coelenterates – jellyfish Aequorea victoria and hydroid Obelia longissima, and photoluminescence spectra of the bioluminescent reaction products (Ca2+-discharged photoproteins) were deconvolved into components. The bioluminescence spectra of aequorin were found to include three, the bioluminescence spectra of obelin – four, and the photoluminescence spectra of the Ca2+-discharged photoproteins – only two components. The spectral components were assigned to one unionized and three ionized forms of coelenteramide. The changes in acidity of the excited coelenteramide molecule are discussed. The differences in bioluminescence and photoluminescence spectra are considered, with protonic environment of coelenteramide taken into account.