Before revision:  Here we explain how the geometrical shape of secondary superstructures such as helix-loop-helix motifs, and even entire folded proteins , can be described analytically in terms of a single explicit elementary function that is familiar from nonlinear physical systems where it is known as the kink-soliton.
After revision:  Here we explain how the geometrical shape of entire folded proteins , can be described analytically in terms of a single explicit elementary function that is familiar from nonlinear physical systems where it is known as the kink-soliton.