Extended Data Fig. 3: Circular Dichroism (CD) spectroscopy shows unique heme arrangements for OmcZ nanowires.
From: Structure of Geobacter cytochrome OmcZ identifies mechanism of nanowire assembly and conductivity
a, CD spectra OmcZ nanowire shows similar secondary structure at pH 10.5 and pH 7 buffer. b, CD spectra of OmcS and OmcZ nanowire hemes. Reduced spectrum show narrowing, and a red-shift of the peaks compared to the oxidized spectrum for c, OmcZ. d, OmcS nanowires as expected. e, The double positive peak feature is unique to the OmcZ nanowires, while the non-filamentous OmcZ30 fails to show a such feature. f, Simulated CD spectra for various sextets of hemes from OmcZ showing that the line shape is independent of six hemes included in the computations. Simulated CD spectra of g, OmcS (green) and h, OmcZ (pink), using only hemes and heme binding motifs show the peak features observed in the experimental data (black). The simulated spectra were uniformly shifted to longer wavelength by 0.06 eV (see methods for details) i, Resolving the contribution of individual hemes to the CD spectra for OmcS and OmcZ reveals that the double peak is a specific feature of hemes in OmcZ nanowires. Evolution of the CD spectra as adjacent hemes in OmcS (green) and OmcZ (pink) were sequentially added to the computations. The labels in each panel indicate which hemes were added for the spectra. The sequence of addition is from left-to-right in both rows.
