Biochemistry of dinoflagellate bioluminescence: the purification and characterization of dinoflagellate luciferin from Pyrocystis lunula

Abstract

The purification and characterization of the luciferin from P. lunula along with evidence that it is a polypyrrole-type molecule were covered. Luciferin is extremely labile at low pH, at high salt concentration and to O2; when possible the purification steps were carried out in the presence of a buffered reducing agent and under Ar. Purified luciferin is soluble in water and polar organic solvents. It is yellow (.lambda.max 245 and 390 nm with a shoulder at 290 nm in neutral or basic aqueous solution) and displays a strong blue fluorescence (.lambda.max for excitation at 390 nm, for emission at 474 nm) that closely matches the bioluminescence emission spectrum [Bode and Hastings (1963)]. Autoxidation leads to concomitant decreases in the 390-nm absorbance, 474-nm fluorescence and biological activity; similar changes occurred with oxidation by K3Fe(CN)6, allowing a quantitation of luciferin by titration. Luciferin has a MW between 500 and 600, displays positive Ehrlich and Schlesinger reactions and yields on acid chromate oxidation fragments apparently resembling substituted maleimides; the proposal that dinoflagellate luciferin contains a substituted polypyrrole of the bile pigment type is supported.