I-symmetry, the highest chiral point group, and the icosahedral structure of virus particles.

Small molecules exhibiting I-symmetry, the member of highest order amongst the five chiral point groups, have yet to be made. However, many virus particles such as the human adenovirus exhibit icosahedral symmetry. The handedness of the subunits being exchanged or permutated by symmetry operations in these supramolecular structures remain invariant since their protein constituents contain L-amino acids. This is only consistent with the existence of symmetry operations of the first kind, and thus these chiral icosahedral ensembles provide suitable examples of I-symmetry.