Demonstration of your work

In a first set of experiments, the S-layer protein mixtures showed an interesting assembly behavior, where proteins with equal molar mass (mixture SbsB:RsaA) provide no change in the size of the assembly. In contrast to this result assemblies with a deviating molar mass SbsB:PS2 and RsaA:PS2 showed a strong tendency to form aggregates, where equimolar ratios behave different than the individual particles. This can be interpreted as a hint for cluster formation and mixing. The particle size is increasing for RsaA:PS2, which is likely a hint for mixing of the particles as the affinity of the individual building blocks leads to a formation of protein micelles with higher aggregation numbers. In contrast the size decrease for SbsB:PS2 occurs due to unfavored interactions, resulting in islands or clusters within the aggregate. The arrangement within the individual assemblies was simulated resulting in a stacking behavior of the proteins. The result could be verified by stacking the layers on latex nano beads, where an increasing amount of nano beads leads to an accordingly increasing amount of layers. Here, layer thicknesses of approximately 100 nm could be achieved. A hollow assembly in contrast would have resulted in a constant value, where the latex nano beads could be found in the interior or exterior of the assembly. The radius would remain constant independent of the amount of latex. The fixation of the proteins on a particle surface is further beneficial, as the particles provide a high surface area for catalysis compared to planar surfaces and can be removed via centrifugation.
The SbsB-Streptavidin conjugate provides multiple advantages. Biotinylated proteins or catalysts can be anchored on the surface and the proteins can be mixed in the desired manner. The consideration has to be made, whether clusters are desired or complete mixing of the structures. The above-mentioned rules should serve as guiding line for the combination to the desired interactions.