Flash-quench technique

Nguyen KL, Steryo M, Kurbanyan K, Nowitzki KM, Butterfield SM, Ward SR, Stemp EDA (2000) DNA-protein cross-linking from oxidation of guanine via the flash-quench technique. J Am Chem... 

Figure 8 Illustration of the flash-quench technique for measuring intramolecular ET rates. Photoexcitation of Ru(II)(bpy)2(imidazole)(amine)2+, Ru(II)(bpy), bound to ferro-cytochrome c, Fe(II)P, produced an 80-ns lived metal-to-ligand charge transfer (MLCT) excited state, Ru(III)(bpy -), which was oxidatively quenched by bimolecular reaction with Ru(NH3) +. The resulting Ru(III)-complex was then reduced by the Fe(II)P through thermal, protein-mediated ET. Finally bimolecular reaction of the Ru(II)/Fe(III)P product with Ru(NH3) + re-formed the starting Ru(II)-protein-Fe(II)P complex.

Stemp EDA, Arkin MR, Barton JK. Oxidation of guanine in DNA by Ru(phen)2dppz3+ using the flash-quench technique. J Am Chem Soc 1997 119 2921-5. 

On the basis of the strong photo-oxidising behaviour of [Re(phen)(CO)3(imidazole)]+ (9) (Re(I) /Re(0) = ca. +1.3 V vs. NHE in CH3CN), Gray and co-workers reacted [Re(phen)(C0)3(H20)]+ with azurin, resulting in the formation of [Re(phen) (CO)3(His83)]+-AzCu+, and studied the electron-transfer in this mutant [28], Excitation of the rhenium(I) complex leads to direct oxidation of the copper centre of the protein to copper(II). Using the flash-quench technique with... 

The rates of intramolecular Fe2+ - Ru3+ electron transfer were measured by a flash-quench technique (33) the results are listed in Table I along with other pertinent ET parameters. Measured ET rates span 2... 

Rates of Cu+ to Ru + electron transfer also have been measured in modified mutants of spinach plastocyanin, a blue copper protein from the photosynthetic ET chain [79], Ru-bipyridine complexes were introduced at surface sites, with Cu-Ru distances ranging from 13 to 24 A. ET rate constants, measured using laser flash-quench techniques, vary from 10" to 10 s. ET in Ru-modified plastocyanin is not activationless as it is in Ru-modified azurin, suggesting a slightly greater reorganization energy for the photosynthetic protein. The distance dependence of ET in Ru-modified plastocyanin is exponential with a distance decay factor identical with that reported for Ru-modified azurin (1.1 A ). 

Seminal work by Mutz et al. [107,108] produced the first systematic study of the ET mechanisms of a synthetic metalloprotein (90). Based on the original designs of Lieberman and Sasaki [109] and Ghadiii et al. [110], these workers prepared a de novo ET protein in which viologen groups were attached to the carboxyl ends of a three-helix bundle capped by a Co (bpy)3 electron acceptor (Fig. 18). Both electron pulse radiolysis and laser flash-quench techniques were used to create a prompt reduction of a viologen donor that subsequently transferred an electron to the Co acceptor via simple first-order kinetics. An important aspect of this system was that a variation of solvent conditions was found... 

Famum BH, Gardner JM, Meyer GJ (2010) Flash-quench technique employed to study the one-electron reduction of triiodide in acetonitrile evidence for a diiodide reactimi product Inorg Chem 49 10223-10225... 

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