Gas‐Lubricated Vibration‐Based Adhesion for Robotics

Abstract

Supplemental Figure 1. Diagrams of gel filtration and analytical ultracentrifugation gave the possible solution states for NAC, αNAC, and TαNAC separately. (A) The retention volume (VR) of purified NAC heterodimer with a 1:1 stoichiometry of the two subunits showed by SDS-PAGE is 13.1 mL in Superdex 200 10/300 GL. (B) The VR of αNAC with 8 non-native residues left from expression vector was 12.9 mL in Superdex 200 10/300 GL. (C) Analytical ultracentrifugation showed that αNAC the same to panel B had only one solution state with an average molecular weight (MW) around 57 kD. Which made sure that recombinant αNAC protein (MW was 25.2 kD for monomer) was stable in solution tested as a homodimer. Meanwhile, the VR of NAC was a bit larger than the VR of αNAC showed that the Mw of NAC is possible a bit smaller than 57 kD, so we concluded that NAC was stable as a monomer in solution tested. (D) The VR of TαNAC was 12.7 mL in Superdex 75 10/300 GL. (E) Analytical ultracentrifugation showed that the most majority of TαNAC the same to panel D had one solution state with a MW around 14.9 kD and the rest had another solution state with a Mw around 28.9 kD. According to the MW of TαNAC monomer (6.7 kD), we concluded that the most majority of TαNAC also was a homodimer, however, a small part of them was a homotetramer in solution tested. Supplemental Figure 2. Hydrophobic side chains for stabilizing the structures of NAC α -NAC β or TαNAC homodimer (The colors of cartoon diagrams were the same to Fig. 1) (A) All the hydrophobic side chains buried inside the β-barrel of NAC α -NAC β (the left diagram) and several hydrophobic side chains interaction and two hydrogen bonds (one formed between Oε1/Gln109' of α2' and Nδ2/Asn63' of β2' , and the other formed between O/Gln-109' of α2' and Nε/Arg-93 of β2, the right diagram) contributed to the stabilization of α1' an α2' in molecular NAC β . (B) All the hydrophobic side chains buried inside the β-barrel of TαNAC homodimer.