Recent research has highlighted the exciting possibilities enabled by the use of protein structures as nanocomponents to form functional nanodevices. To this end, control over protein-protein and protein-surface interactions is essential. In this study, the authors probe the interaction of human peroxiredoxin 3 with gold surfaces, a protein that has been previously identified as having potential use in nanotechnology. Analytical ultracentrifugation and transmission electron microscopy revealed the pH mediated assembly of protein toroids into tubular structures across a small pH range. Quartz crystal microbalance with dissipation measurements showed differences in absorbed protein mass when pH is switched from pH 8.0 to 7.2, in line with the formation of supramolecular structures observed in solution studies. Scanning tunneling microscopy under ambient conditions showed that these protein tubes form on surfaces in a concentration dependent manner, with a tendency for protein adsorption and supramolecular assembly at the edges of Au(111) terraces. Finally, self-assembled monolayer modification of Au surfaces was explored as a means to control the adsorption and orientation of pH triggered protein structures.

No abstract

Proteins hold great promise in forming complex nanoscale structures which could be used in the development of new nanomaterials, devices, biosensors, electronics, and pharmaceuticals. The potential to produce nanomaterials from proteins is well supported by the numerous examples of self-assembling proteins found in nature. We have explored self-assembling proteins for use as supramolecular building blocks, or tectons, specifically the N-terminal domain of Lsr2, Nterm-Lsr2. A key feature of this protein is that it undergoes self-assembly via proteolytic cleavage, thereby allowing us to generate supramolecular assemblies in response to a specific trigger. Herein, we report the effects of pH and protein concentration on the oligomerization of Nterm-Lsr2. Furthermore, via protein engineering, we have introduced a new trigger for oligomerization via enteropeptidase cleavage. The new construct of Nterm-Lsr2 can be activated and assembled in a controlled fashion and provides some ability to alter the ratio of higher ordered structures formed.