Low range protein ladder

For polyacrylamide gel electrophoretic separation (SDS-PAGE), the samples were boiled in 2.5% sodium-dodecyl sulphate (SDS) sample buffer that included β-mercaptoethanol for 12 min. The samples were run on a 4–20% gradient protein gel (Biorad, Hercules, CA) at a constant voltage of 200 V for 30 minutes. Precision Plus Protein Prestained molecular weight standards (BioRad, Hercules, CA) and Low Range Protein Ladder (Thermo Scientific) were used to compare the molecular weight of cytochromes in the filament preparations. Gels were immediately washed at least 3 times with ultra-pure deionized water over a 1-hour period, stained with Coomassie R-250 stain (Thermo Scientific, Rockford, IL), and destained overnight.

For polyacrylamide gel electrophoretic separation (SDS–PAGE) samples were boiled in 1× SDS sample buffer that included β-mercaptoethanol for 12 min. The samples were run on a 16% Tricine protein gel (Thermo Fisher Scientific) initially at constant voltage of 30 V for 2 h before changing to 190 V for 30 min at 4 °C. Precision Plus Protein Prestained molecular weight standards (BioRad) and Low Range Protein Ladder (Thermo Fisher Scientific) were used to compare the molecular weight of cytochromes in the filament preparations. Gels were stained with Coomassie R-250 stain for 1 h (Thermo Scientific), and destained in deionized water overnight.