Two-Dimensional Heterospectral Correlation Analysis of the Redox-Induced Conformational Transition in Cytochrome c Using Surface-Enhanced Raman and Infrared Absorption Spectroscopies on a Two-Layer Gold Surface

Abstract

The heme protein cytochrome c adsorbed to a two-layer gold surface modified with a self-assembled monolayer of 2-mercaptoethanol was analyzed using a two-dimensional (2D) heterospectral correlation analysis that combined surface-enhanced infrared absorption spectroscopy (SEIRAS) and surface-enhanced Raman spectroscopy (SERS). Stepwise increasing electric potentials were applied to alter the redox state of the protein and to induce conformational changes within the protein backbone. We demonstrate herein that 2D heterospectral correlation analysis is a particularly suitable and useful technique for the study of heme-containing proteins as the two spectroscopies address different portions of the protein. Thus, by correlating SERS and SEIRAS data in a 2D plot, we can obtain a deeper understanding of the conformational changes occurring at the redox center and in the supporting protein backbone during the electron transfer process. The correlation analyses are complemented by molecular dynamics calculations to explore the intramolecular interactions.

Adsorption of heptane–toluene binary mixtures on a hydrophobic polymer surface

“…[55][56][57] When s 1 comes from IR-Raman data, and s 2 from SFG data, we compute the heterospectral correlation. [58][59][60][61] The spectral quantities appearing in Eq. 9are mean-centered about the n values of x at each frequency ω…”

Interfacial assembly of mesoporous nanopyramids as ultrasensitive cellular interfaces featuring efficient direct electrochemistry

“…To further probe the switching effect on the 3D mesoporous NPIs, Cyt c, 48,49 which is one of the most intensively investigated redox proteins, was used as a model to be immobilized on the 3D Au-NPI arrays (Supplementary Figure 13). A Cyt c molecule exists in either an oxidized or reduced state and thus operates as an electron acceptor or donor in PEC systems to switch the photocurrent direction of a photoelectrode.…”

Optical Reading of Contaminants in Aqueous Media Based on Gold Nanoparticles

“…However, the spontaneous Raman scattering is very weak, which is difficult to be separated from the intense Rayleigh scattering. Surface enhanced Raman spectroscopy (SERS) is a surface sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces . The phenomenon of SERS is generally expained by a combinaiton of an electromagnetic mechanism and a chemical mechanism related to charge transfer between the substrate and the analyte molecules.…”