Ribbon drawings are an elegant way to visualize the folding and secondary structure of proteins. They have been observed to become `smoother' during the course of structural refinement. The ribbons present a global view of the molecule: color cues and irregularities are immediately obvious to the eye.
Ribbon drawings make striking illustrations. Is this the only reason they grace so many journal covers? Keats' line that truth is beauty may be applicable here. The geometry of a ribbon curve may offer clues to the protein folding problem.
Multiresolution curve analysis of end-point interpolating B-spine curves via the wavelet transform(40) generates the best approximating curve from reduced sets of control points. Such a B-spline models a protein fold by points from the peptide planes and termini of the chain(17). This offers possibilities for display, editing, and topological comparison at lower resolutions.
Figure 8 is a multiresolution curve analysis with ribbons 3.0. Each monomer of dimeric interferon-gamma(41) is labeled per helix (eg, A and A'). Cylinders fit to the helical residues have their C-terminal end shaded. Above is the BSribbon curve based on the 123 residues. Below is the B-spline curve defined by 32 points. This curve generally passes through the cylinders. Preliminary results suggest a recognizable fold is generated from a number of points equal to one-sixth the number of residues(42).
Figure 8. Multiresolution curve analysis of Interferon-gamma