Effectiveness of the Accessory Yellow Fluorescent Protein in the Bacterial Luciferase Reaction Correlates with the Lifetime of the Peroxyhemiacetal Intermediate: The Stereochemistry of the Reaction

Abstract

AbstractIn the in vitro reaction of Vibrio fischeri Y‐1 luciferase, the dependence of the initial luminescence intensity (Io) and its rate of decay (kd) on the chain‐length of the aliphatic aldehyde are greatly altered by the presence of yellow fluorescent protein (YFP), which functions as an accessory emitter. Whereas with no YFP both kd and Io are maximum for chain lengths ≥ 12, the fraction of the light emitted from the accessory chromophore, measured as the ratio of yellow to blue light (Y/B), is greater with shorter chain‐length aldehydes. Thus, aldehydes that are least efficient in the absence of YFP are more efficient for causing yellow emission in its presence. These results are interpreted on the basis of the expected lifetimes of the peroxyhem‐iacetals with which YFP interacts: high values of kd reflect short peroxyhemiacetal lifetimes, hence less chance of interaction with YFP. The critical dependence on aldehyde chain‐length underlines the importance of stereochemical factors in the bacterial reaction, which are discussed here in the framework of a chemically initiated electron exchange luminescence model.