Pairwise interactions in collagen and the design of heterotrimeric helices.

A comprehensive survey of single amino acid substitutions in the canonical Xaa-Yaa-Gly repeat has laid the ground work for our understanding of the collagen triple helix. Building upon this foundation requires understanding pairwise amino acid interactions which will allow us to prepare heterotrimeric helices with great specificity in addition to an overall improved control over helix structure and stability. Furthermore, detailed studies on these interactions will help us understand collagen's n structure, assembly mechanism and stability. The most important pairwise interaction so far identified in the collagen triple helix is the axial charge pair that can be formed between properly placed Lysine and either Aspartate or Glutamate residues. This review will summarize our understanding of this interaction and other charged pair interactions and how they have been successfully used to control collagen triple helix self-assembly.