We estimate the residue-monomer and residue-residue interaction energies of the collagen-like peptide T3-785, whose triple helix structure is the sequence X-Y-glycine (X, Y are often the imino acids proline and hydroxyproline), considering its full X-ray diffraction crystal structure, including a hydratation layer of 111 water molecules. The computations are performed within the density functional theory (DFT) scope together with a Molecular Fractionation with Conjugate Caps (MFCC) approach. We found that the hydroxyproline and proline residues play a very important role in the stabilization of the T3-785 structure, with the arginine residue in a given peptide chain exhibiting the strongest residue-strand interaction. (c) 2013 Elsevier B.V. All rights reserved.