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

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• 作者：Yuval Erez ; Itay Presiado ; Rinat Gepshtein ; Lu铆s Pinto da Silva ; Joaquim C. G. Esteves da Silva ; Dan Huppert
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：July 19, 2012
• 年：2012
• 卷：116
• 期：28
• 页码：7452-7461
• 全文大小：634K
• 年卷期：v.116,no.28(July 19, 2012)
• ISSN：1520-5215

文摘

Optical steady-state and time-resolved spectroscopic methods were used to study the photoprotolytic reaction of oxyluciferin, the active bioluminescence chromophore of the firefly鈥檚 luciferase-catalyzed reaction. We found that like class="smallcaps">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 脳 10¹⁰ s^鈥?, which is somewhat slower than that of class="smallcaps">d-luciferin. The kinetic isotope effect (KIE) on the fluorescence decay of oxyluciferin is 2.5 卤 0.1, the same value as that of class="smallcaps">d-luciferin. Both chromophores undergo fluorescence quenching in solutions with a pH value below 3.