Table 2.

Helix parameters and pitch-angles of peptide and methylene groups determined from x-ray diffraction data (Protein DataBank (PDB)) of collagen-like model peptides

Collagen-like model peptide	Residues per helix turn	Rise per residue (Å)	Helix radius (Å)	Peptide pitch-angle θ(p)	Methylene pitch-angle θ(m)
Heterotrimer(collagen I-like)	3.5	2.57	1.5	46.34°	97.46° ± 43.87°
Homotrimer(collagen II-like)	3.5	2.71	1.5	44.82°	108.98° ± 57.83°

The heterotrimer corresponds to PDB No. 1ITT (GPPGPPG) while the homotrimer is PDB No. 1WZB (HHGHHGHHGH).