Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.
J Phys Chem A. 2012 Jul 19;116(28):7452-61. doi: 10.1021/jp301910p. Epub 2012 Jul 6.
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.
采用光稳态和时间分辨光谱方法研究了虫荧光素的光解反应，虫荧光素是萤火虫荧光素酶催化反应的活性生物发光发色团。我们发现，与萤火虫生物发光反应的底物 D-虫荧光素一样，虫荧光素也是一种光酸，pK(a)* 值约为 0.5，而激发态质子转移 (ESPT) 速率系数为 2.2×10(10) s(-1)，略慢于 D-虫荧光素。在虫荧光素的荧光衰减中，动力学同位素效应 (KIE) 为 2.5±0.1，与 D-虫荧光素相同。两种发色团在 pH 值低于 3 的溶液中都会发生荧光猝灭。
