Figure 7.

Model of putative enzyme arrangement on a biotinylated surface segment of a TMV stick. Schematic drawing demonstrating the putative arrangement of [SA]-GOx and [SA]-HRP installed on biotin linkers of 6 nm total length on the TMV surface, taking into account their molar ratio applied, the binding efficiencies achieved, the enzyme conjugates' dimensions and the volume generated by the maleimide-PEG₁₁-biotin linkers above the TMV_Cys surface. Using a 22-fold excess of biotin linkers relative to the viral CP_Cys (yellow) molecules, every second CP_Cys was fashioned by a linker (CP_Cys/Bio, green). Of those, virtually every biotin was shown to couple an [SA]-enzyme. This is likely to result in a staggered arrangement of the enzymes on the TMV surface. The flexible and 6 nm long PEG₁₁ spacers as part of the linkers would therefore be essential to increase the surface volume of TMV accordingly. Refer to text and Supplementary Figure 5 for details.