Fig. 11.

Protein chain shape and size classification approach. A The volume of the sphere enclosing the protein chain as well as the protein chain volumes are calculated, and their ratio obtained (VR). Globular proteins present more spherical shapes and therefore occupy a higher portion of the sphere volume, resulting in higher volume ratios. Non-globular, elongated or fibrous proteins on the other hand do not and present lower VRs. After extensive visual examination, a threshold was established at VR = 0.08, and so proteins classified in these two groups. Proteins were classified as “tiny” if their chain was ≤ 100 amino acids; B eight examples of each protein chain group to illustrate the outcome of the approach