S4-symmetric peptide

This is a 24-amino acid S4-symmetric peptide macrocycle that I designed using methods that I implemented in the Rosetta software suite.  The four lobes are coloured red and blue, with the red lobes mirroring the blue lobes (i.e. the L-amino acids flipped to D-amino acids and vice versa).  The peptide is designed to bind a central zinc atom (not shown here, but providing the white glow in the middle).  My coworker synthesized this and a collaborator at UCLA solved the structure, and it does indeed fold into this conformation in the presence of zinc; in its absence, it flips around inside out.  I rendered this pretty image from the computational design model using Blender.  If you'd like to read more about this design, see Mulligan VK, Kang C, Sawaya M et al. (2020) Computational design of mixed chirality peptide macrocycles with internal symmetry.  Protein Sci. 29(12):2433-2445 (onlinelibrary.wiley.com/doi/10…).

Image copyright (c) 2020 Vikram K. Mulligan.