Preliminary spectrofluoroelectrochemical studies indicate a possible conformational change in horse heart cytochrome c upon reduction

In Situ Autofluorescence Spectroelectrochemistry for the Study of Microbial Extracellular Electron Transfer

“…Tryptophan and heme C, which both are present in horse heart cytochrome c , were identified by fluorescence spectroscopy (Figure b). This revealed two chromophores present in both samples, which were attributed to the tryptophan residue (excitation at 288 nm, fluorescence 320–360 nm, referred to here as TRP ) and the heme C (excitation at 334 nm, fluorescence 400–500 nm) ,…”

“…One may interpret this behavior either with a saturation of HEME C1 and C2 in the oxidized state, which does not allow further energy transfer, or by conformational changes that alter the distance between the tryptophan residue and the heme center. Such conformational changes have been proposed for purified cytochromes with different techniques, spectroscopic, as well as spectrofluoroelectrochemical, but not for full grown electrochemically active biofilms.…”

“…This revealed two chromophores present in both samples, which were attributed to the tryptophan residue (excitation at 288 nm, fluorescence 320-360 nm, referred to here as TRP) and the heme C (excitation at 334 nm, fluorescence 400-500 nm). [23,24] In contrast to suspended biofilms, the heme C fluorescence spectra of intact, electrode-attached biofilms (recorded in a custom-made fluorescence spectroelectrochemical reactor using transparent, quartz based ITO electrodes -see SI) exhibit two maxima (Figure 3a), located at 405 nm (here referred to 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 here as HEME C1) and 450 nm (HEME C2). These values are in good agreement with literature values for G. sulfurreducens biofilms.…”

Emission Spectroelectrochemistry: Cell Design and Setup

“…In practice, this type of cells was built with working electrodes based on vapour-deposited metallic films [40], transparent conducting oxides films [40,41] or presented small holes in its surface [42] such as for example, minigrid electrodes [43][44][45][46]2,47]. In addition, the PVD technique has the advantages of producing reproducible metallic surfaces with high crystallographic quality, low roughness, low electrical resistance and with a defined geometry [15].…”

Rhodamine 6G Radical: A Spectro (Fluoro) Electrochemical and Transient Spectroscopic Study

“…The electrochemical regulation of luminescence is highly relevant for development of suitable molecular candidates for super‐resolution microscopy, redox systems, switchable molecular dyads, conjugated polymers, displays, and other electrofluorochromic devices . Most systems for electrochemically controllable emission and absorption (electrofluorochromism) use lanthanide complexes as both redox‐active and emissive centres .…”