Comparative study of the photoprotolytic reactions of D-luciferin and oxyluciferin.
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.
Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.
Yuval
Y
Erez
Itay
I
Presiado
Rinat
R
Gepshtein
Luís
L
Pinto da Silva
Joaquim C G
JC
Esteves da Silva
Dan
D
Huppert
D052160:Benzothiazoles / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D007700:Kinetics; D008163:Luminescent Measurements; D015394:Molecular Structure; D055668:Photochemical Processes; D011719:Pyrazines / Q000737:chemistry*
D052160:Benzothiazoles; C532924:D-luciferin; D007211:Indoles; D011719:Pyrazines; C014730:oxyluciferin