NMR and x-ray studies of collagen model peptides

The main structural component in collagen is the triple helix which is generally composed of the amino acid sequence repeat (X-Y-Gly)_n with proline and hydroxyproline often present at poistions X and Y. Non-globular, fibrillar proteins like most collagens are difficult to work with from a structural perspective. An alternative approach to collagen structural elucidation is to study considerably shorter fragments of the triple helix. To date, various triple helical model peptides such as (Pro-Pro-Gly)_n and (Pro-Hyp-Gly)_n have been investigated by various physical and spectroscopic techniques. The advent of easy solid phase peptide synthetic methodology and the development of multi-dimensional heteronuclear and high field NMR technologies have promoted significant advances in the structure elucidation of a number of triple helix peptides. Here, the main focus is to review and to address the current state of knowledge in the field of NMR and x-ray analysis of triple helical model peptides.