ABSTRACT
It is known that bioluminescence of obelin is triggered by Ca2+ the binding of which to the protein induces the decarboxylation of 2-hydroperoxycoelenterazine. The molecular mechanism of fluorescence of obelin, which determines the fluorescence of see hydroid Obelia Longissima, has been investigated with the use of quantum chemical calculations. According to quantum chemical calculations, the emitter of the reaction is the ion-pair state of phenolate-anion of coelenteramide. It has been shown that the fluorescence spectrum of this state depends on the position of the proton between the oxygen atoms of the phenol group of coelenteramide and the nitrogen atom of His22. The agreement of the calculated absorption and fluorescence spectra with the experimental spectrum shows the accuracy of the quantum chemical calculations and conclusions.
