Oxidation-reduction indicators: Lissamine Blue BF

Abstract

The e.m.f. of the cell, buffer x from pH 1 to 11, is given by where E" = 0.155 V ; the dissociation constants K1, K2 of the reduced form are 5 x 10-8 and 1.26 x 10-5, and that of the oxidized form K3 is 3.16 x 10-4. Deviations of several millivolts occur in alkaline buffer solutions of appreciable ionic strengths. Even in solutions more dilute than 10-4 M, potentials are well poised (except at the extremes of the titration curves). Potentials on the normal hydrogen scale are tabulated at intervals of 0.5 pH.

Chemical and Biological Reduction of the Radical SAM Enzyme CPH4 Synthase

“…32 Of the three classes that comprise the superfamily, two use SAM as a cosubstrate The redox mediators used were methyl viologen (E m = −0.446 V), 20 benzyl viologen (E m = −0.359 V), 20 neutral red (E m = −0.325 V), 21 and lissamine blue BF (E m = −0.276 V, at pH 7.5). 22 The dashed lines represent the rates of formation for CDG (−−−) and dAdo (---) (0.2 and 0.08 min −1 , respectively) when BsQueE was activated by dithionite alone. whereas the class I enzymes re-form SAM on each turnover.…”

“…22 All components except CPH 4 were mixed and incubated at room temperature for 10 min. The reaction was initiated by addition of CPH 4 .…”

“…Reaction mixtures contained 50 mM PIPES-NaOH (pH 7.4), 10 mM DTT, 2 mM MgSO 4 , 2 mM SAM, 2 mM CPH 4 , 2 μM Bs QueE, 10 mM dithionite, and either no mediator, 2 mM methyl viologen ( E m = −0.446 V), 2 mM benzyl viologen ( E m = −0.359 V), 1 mM neutral red ( E m = −0.325 V), or 1 mM lissamine blue BF ( E m = −0.276 V, at pH 7.5) . All components except CPH 4 were mixed and incubated at room temperature for 10 min.…”

“…20 2 mM benzyl viologen (E m = −0.359 V), 20 1 mM neutral red (E m = −0.325 V), 21 or 1 mM lissamine blue BF (E m = −0.276 V, at pH 7.5). 22 All components except CPH 4 were mixed and incubated at room temperature for 10 min. The reaction was initiated by addition of CPH 4 .…”

“…Velocity of CDG formation (•) or dAdo formation ( ■ ) as a function of the reduction potential of the redox mediator used in the activity assay. Dithionite was the reductant used in all of the reactions.The redox mediators used were methyl viologen (E m = −0.446 V),20 benzyl viologen (E m = −0.359 V),20 neutral red (E m = −0.325 V),21 and lissamine blue BF (E m = −0.276 V, at pH 7.5) 22. The dashed lines represent the rates of formation for CDG (−−−) and dAdo (---) (0.2 and 0.08 min −1 , respectively) when BsQueE was activated by dithionite alone.…”