The Red Absorbing Flavin Species in the Reaction of Bacterial Luciferase with Fmnh2 And

The reaction of luciferase-bound Z is known to result in the formation of a long-lived intermedlate in the bioluminescent reaction (1). This intermediate was isolated and ,haracterized as the luciferase-peroxyflavin (2), whose struc~ture was later shown to be the flavin 4a-substituted peroxyadduct (3). In the earlier work this peroxy intermediate had been shown to exhibit a single peak at about 370 rum, a shoulder a-t about 460 run, the absorption tailing off around 500 rum, with none above 520 run. In more recent publications,however (4,5), it has been reported that the reaction of the luciferase-bound reduced flavin mononucleotide with O2 also results in the appearance