SERS uncovers the link between conformation of cytochromecheme and mitochondrial membrane potential

Abstract

Cytochrome c is an essential component of the electron transport chain (ETC), which regulates respiratory chain activity, oxygen consumption, and ATP synthesis. But the impact of conformational changes in cytochrome c on its function is not understood for lack of access to these changes in intact mitochondria. Here we describe a label-free tool that identifies conformational changes in cytochrome c heme and elucidates their function. We verify that molecule bond vibrations assessed by surface-enhanced Raman spectroscopy (SERS) is a reliable indicator of the planar heme configuration during activation of ETC and decrease in inner mitochondrial membrane potential. The planar conformation of cytochrome c heme enables its optimal orientation towards the heme of cytochrome c1 in complex III. This ensures a faster electron transfer, which is important during ETC speed-ups and acceleration of ATP synthesis. The ability of our tool to track mitochondrial function opens wide perspectives on cell bioenergetics.

Detection of Hypertension-Induced Changes in Erythrocytes by SERS Nanosensors

“…The first ratio, I 1638 /I 1375 , shows the probability of the planar heme conformation. The higher this ratio is, the higher the probability of a planar conformation of the heme is [ 33 , 34 ]. Moreover, the use of ratios of peak intensities causes the spectral analysis to be independent of the local SERS signal intensity.…”

“…Our results clearly indicate the absence of the effect of hypertension on the probability of the planar heme conformation ( Figure 3 b). The ratio of I 1175 /I 1375 peak intensities represents the probability of the asymmetric pyrrole half-ring vibrations and can be used as a marker of heme mobility: the higher this ratio is, the higher the in-plane mobility of the heme is [ 33 , 34 ]. We found that this ratio is more dispersed in erythrocytes than in erythrocyte ghosts ( Figure 3 c), which may be explained by the more heterogeneous Hb population in the submembrane region of intact erythrocytes than in erythrocyte ghosts ( Figure 1 b).…”

Halloysite Nanotubes with Immobilized Plasmonic Nanoparticles for Biophotonic Applications

“…Silver nanoparticles (Ag-NPs) are widely used as a nanomaterial with superior plasmonic properties, and the SERS activity of Ag-NPs is shown and developed in a variety of studies [14][15][16][17][18][19]. The SERS phenomenon can also allow using such NPs in the solar energy conversion systems [20] and as biosensors for the detection of different substances both in water and in vitro [17,21]. Ag-NPs deposited on the HNTs surface can result in localized surface plasmon resonance (LSPR) in the region of 400 to 600 nm [11,22] and thus it could be used for SERS [3].…”

Live Cell Poration by Au Nanostars to Probe Intracellular Molecular Composition with SERS

“…Aggregates of silver nanoparticles [18] and composite silica-silver nanostructures made it possible to amplify the Raman signal at large distances from submembrane molecules inside intact mitochondria or erythrocytes [19]. Nanostructured silver surfaces were used for labelfree studies of conformational changes in cytochrome C heme in functional mitochondria adsorbed on its surface [20,21]. The SERS platform, consisting of graphene-coated gold nanopyramids, was used to study the intracellular composition, which made it possible to distinguish the p53 knockout cancer cell line [22].…”