The Effect of Deuterium Oxide on the Stability of the Collagen Model Peptides H-(Pro-Pro-Gly)(10)-OH, H-(Gly-Pro-4(R)Hyp)(9)-OH, and Type I Collagen

The collagen triple helix has a larger accessible surface area per molecular mass than globular proteins, and therefore potentially more water interaction sites. The effect of deuterium oxide on the stability of collagen model peptides and Type 1 collagen molecules was analyzed by circular dichroism and differential scanning calorimetry. The transition temperatures (T-m) of the protonated peptide (Pro-Pro-Gly)(10) were 25.4 and 28.7 degrees C in H2O and D2O, respectively. The increase of the T-m, of (Pro-Pro-Gly)(10) measured calorimetrically at 1.0 degrees C min(-1) in a low pH solution from the protonated to the deuterated solvent was 5.1 degrees C. The increases of the T, for (Gly-Pro-4(R)Hyp)(9) and pepsin-extracted Type I collagen were measured as 4.2 and 2.2 degrees C, respectively. These results indicated that the increase in the T, in the presence of D2O is comparable to that of globular proteins, and much less than reported previously for collagen model peptides [Gough and Bhatnagar, J Biomol Struct Dyn 1999, 17, 481-491]. These experimental results suggest that the interaction of water molecules with collagen is similar to the interaction of water with globular proteins, when the ratio of collagen to water is very small and collagen is monomerically dispersed in the solvent. (C) 2009 Wiley Periodicals, Inc. Biopolymers 93: 93-101, 2010.