Comparative Study of the Photoprotolytic Reactions of d-Luciferin and Oxyluciferin

Abstract

Optical steady-state and time-resolved spectroscopic methods were used to study the photoprotolytic reaction of oxyluciferin, the active bioluminescence chromophore of the firefly's luciferase-catalyzed reaction. We found that like D-luciferin, the substrate of the firefly bioluminescence reaction, oxyluciferin is a photoacid with pK(a)* value of ∼0.5, whereas the excited-state proton transfer (ESPT) rate coefficient is 2.2 × 10(10) s(-1), which is somewhat slower than that of D-luciferin. The kinetic isotope effect (KIE) on the fluorescence decay of oxyluciferin is 2.5 ± 0.1, the same value as that of D-luciferin. Both chromophores undergo fluorescence quenching in solutions with a pH value below 3.

Prediction of bioluminescent proteins by using sequence-derived features and lineage-specific scheme

“…First, BLPs are sensitive to the microenvironment [8]. For instance, D -Luciferin exhibits the peak spectrum in green region in acidic solution while in red region at basic pH [9]. Second, the vivo organisms largely scatter or absorb the majority regions of the spectrum.…”

Effect of very high magnetic field on the optical properties of firefly light emitter oxyluciferin

“…Iwasaka and his co-workers demonstrated, using living fireflies, that firefly bioluminescence was suppressed in intensity and red-shifted for $10 nm when exposed to a 14 T magnetic field. As an ideal "cold light" system with extremely high quantum yield of up to 41.077.4% [5], firefly bioluminescence lies in the center of biochemistry research [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The revealing of magnetic field effects on firefly bioluminescence therefore represents significant progress in this field.…”

Theoretical Study of the Nontraditional Enol‐Based Photoacidity of Firefly Oxyluciferin

“…[23] The absorption spectrum of firefly oxyluciferin in water has a band at approximately 380 nm at acidic/ neutral pH, and a band at approximately 420 nm at basic pH. [22,26] The emission spectrum is characterized by a peak at approximately 550 nm at acidic/neutral pH, and a peak at ap-A theoretical analysis of the enol-based photoacidity of oxyluciferin in water is presented. The basis for this phenomenon is found to be the hydrogen-bonding network that involves the conjugated photobase of oxyluciferin.…”

“…Firstly, luciferin and dehydroluciferin (two natural analogues of oxyluciferin; Figure 1) are also photoacids with similar pK a /pK a * values to oxyluciferin, and these molecules only contain a hydroxyl group on the benzothiazole moiety. [22,24] Secondly, photoacidity of an enol group in a five-membered ring is rare. [31] However, a comparative photophysical study of oxyluciferin and two analogues provided reliable evidence that the ESPT process occurs between the enol group and the solvent.…”