Following Radical Pair Reactions in Solution: A Step Change in Sensitivity Using Cavity Ring-Down Detection

• DOI: 10.1021/ja206783t
• Publication Date: 2011-10-17T19:12:50Z
• Authors: Kiminori Maeda; Simon R. T. Neil; Kevin B. Henbest; Stefan Weber; Erik Schleicher; P. J. Hore; Stuart R. Mackenzie; Christiane R. Timmel
• Keywords: Flash photolysis; Flavin mononucleotide; Absorbance

The study of radical pair intermediates in biological systems has been hampered by the low sensitivity optical techniques usually employed to investigate these highly reactive species. Understanding physical principles governing spin-selective and magneto-sensitive yields kinetics their reactions is essential identifying mechanism bird migration, might have significance discussion potential health hazards electromagnetic radiation. Here, we demonstrate powerful capabilities cavity-enhanced techniques, such as cavity ring-down spectroscopy (CRDS) monitoring recombination associated magnetic field effects (MFEs). These include submicrosecond time-resolution, high (baseline noise on order 10(-6) absorbance units) small (μL) sample volumes. Combined, show that represent significant advantages over single-pass flash-photolysis conventionally applied. studies described here focus photoinduced involving protein lysozyme one two possible photosensitizers: anthraquinone-2,6-disulphonate flavin mononucleotide. CRDS-measured MFEs are observed pump-probe experiments discussed terms gains sample-volume minimization afforded CRDS when compared with flash photolysis methods. Finally, applied an vitro MFE intramolecular electron transfer DNA-repair enzyme, Escherichia coli photolyase, a closely related cryptochrome which proposed mediate animal magnetoreception.