Revision of collagen molecular structure

Area of Science:

• Biochemistry
• Structural Biology
• Biophysics

Background:

• The 10/3-helical model was proposed in 1955 based on fiber diffraction data of native collagen.
• This model suggested a 28.6 Å axial repeat for collagen.

Purpose of the Study:

• To re-evaluate collagen's helical structure using updated analytical methods.
• To compare the explanatory power of the 7/2-helical model against the 10/3-helical model for native collagen.

Main Methods:

• Single crystal analysis of the peptide (Pro-Pro-Gly)(10) to determine the 7/2-helical structure.
• Refinement of both 7/2 and 10/3 helical models against native collagen fiber diffraction data.
• Application of a linked-atom least-squares method for model refinement.

Main Results:

• The 7/2-helical structure exhibits a 20 Å axial repeat.
• Refined analysis indicated the 7/2-helical model explains native collagen fiber diffraction data as well as or better than the 10/3-helical model.
• Recent studies on model peptides predominantly support the 7/2-helical model.

Conclusions:

• The average molecular structure of native collagen is more consistent with 7/2-helical symmetry.
• The 7/2-helical model provides a more accurate representation of collagen's native structure.
• Further research should consider the 7/2-helical model as the prevailing structural representation for collagen.