The role of oxygen in the photoexcited luminescence of bacterial luciferase.

Irradiation of bacterial luciferase results in a long lived luminescence which is qualitatively similar to the chemically induced bioluminescence. It has been found that oxygen is required for the emission of photoexcited bioluminescence, but that it need not be present during irradiation. Oxygen must be added promptly, however, for the intermediate has a relatively short lifetime. In the absence of oxygen still another long lived luminescence has been observed. This is a phosphorescence-like emission which is strongly quenched by oxygen. The observations indicate that this emission involves intermediate states which are distinct and different from those involved in bioluminescence.