Some Observations on the Properties of Crystalline Bacterial Luciferase*

This is the authors' abstract. We don't add key points for this paper.

We describe a number of properties of our crystalline bacterial luciferase preparations, such as absorption spectra and fluorescence characteristics which are not typical of flavoproteins. Acid extraction of the enzyme or digestion with proteolytic enzymes do not lead to the liberation of flavin‐like compounds, as judged by fluorescence techniques. Other dyes such as reduced neutral red will replace FMNH2 in this system, and irradiation of the enzyme with u.v. light does not change the ratio of light production with FMNH2 and reduced neutral red. Thus, all efforts to detect flavin in our enzyme have failed, suggesting that FMN is not necessarily involved in the emitting complex. It is of interest that addition of hydrosulfite to luciferase solutions shifts the fluorescence emission to the blue and thus close to that of bioluminescence emission. Separations of two different FMN‐dependent DPNH oxidases are described, one of which is closely associated with luciferase and exhibits both DPNH and TPNH oxidase activity.