Interchain hydrogen bonds via bound water molecules in the collagen triple helix

Abstract

If the collagen triple helix is so built as to have one set of NH ⃛ O hydrogen bonds of the type N3H3(A) ⃛ O2(B), then it is possible to have a linkage between N1H1(B) and O1(A) through the intermediary of a water molecule with an oxygen O 1W leading to the formation of the hydrogen bonds N1(B) ⃛ O 1W and O 1W (A). In the same configuration, another water molecule with an oxygen O 1W can link two earbonyl oxygens of chains A and B forming the hydrogen bonds O 2W O1(A) and O 2W O0 (B). The two water oxygens also become receptors at the same time for CH ⃛ O hydrogen bonds. Thus, the neighboring chains in the triple helix are held together by secondary valence bond linkages occurring regularly sit intervals of about 3 Å along the length of the protofibril. The additional water molecules occur on the periphery of the proto‐fibril and will contribute their full share towards stabilizing the structure in the solid state. In solution, they will be disturbed by the medium unless they are protected by long side groups. It appears that this type of two‐bonded structure, in which one NH ⃛ O bond is to a water molecule, can explain several observations on the stability and hydrogen exchange properties of collagen itself and related synthetic polypeptides. The nature of the water bonds and their strength are found to be better in the one‐bonded structure proposed from Madras than in the one having the coordinates of Rich and Crick.

Nanoindentation of wet and dry compact bone: Influence of environment and indenter tip geometry on the indentation modulus

“…The fluid environment may contribute to a higher mobility of short range bonding between neighbour collagen chain groups and, hence faster restoration of the structure. In the presence of water it seems the structure tends to form a more well ordered arrangement [49][50][51]. This explanation also agrees with the proposed sacrificial bond theory as found in bone [8,52].…”

Comparative Study of the Durability Behaviors of Epoxy- and Polyurethane-Based CFRP Plates Subjected to the Combined Effects of Sustained Bending and Water/Seawater Immersion

“…The increments of the diffusion coefficients (D) with increasing bending strain can be also ascribed to the combined effects, e.g., the increase of the free volume in the matrix, the formation of micro-cracks, and the weak "less resin area". The PU matrix possesses a unique group, namely -NH-COO- [34], in which the -NH-group can form more hydrogen bonds with water molecules [35], resulting in considerably higher diffusion parameters (water uptake and D). Although these broken samples did not break normally, it is believed that all the highly strained samples will break like these broken samples in the long run.…”

Triple‐helical peptides: An approach to collagen conformation, stability, and self‐association

“….CO (X position) has been a basic feature of all models, 3,4 but there had been proposal of a second H bond between NH (X position) to the CO of a Gly in a neighboring chain, either directly or mediated by water. 25 The determination of several crystal structures of peptides with amino acids, rather than Pro, in the X position, showed a second interchain backbone hydrogen bond mediated by a water NH(X). .…”