To study hierarchical self-assembly of fibrous proteins, methods need to be developed to elucidate the nature of information flow between different levels of structure. The collagens present an interesting example. Sequence-dependent conformational effects are well-known in the collagen triple helix, forming a repetitive sequence (Gly-X-Y; X or Y often hydroxyproline or proline). It should thus be possible to “travel up” the structural hierarchy, and examine the features of long-range ordered structure in light of what is known about sequence and conformational relationships. The next step along this path of structural complexity is an examination of the packing of the collagen triple helices in a condensed phase and the corresponding effect of this organization on any larger domains formed. Studies of crystal structures and solid free surfaces formed by collagen peptides, slowly dried to form glassy solids with very small embedded crystallites, have been used to compare the molecular scale packing behavior of the triple helices within the longer length scale structure of the solid phase. In this instance the peptides go through a state where they are very concentrated viscous, syrupy liquids and where they form solid cholesteric-analogue phases as they dry. A qualitative correlation between the molecular packing geometry of the triple helix and the apparent chirality of the dried cholesteric phase is observed.
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