Number of Acidic Residues.

Chemical characteristics of fossil peptides. Dinosaur peptide sequences were obtained from the literature and their alpha chain location and amino acid positions on the human collagen model determined. The prevalence of acidic residues (bolded, underlined) in the peptides was lower than predicted for “average” peptides of comparable lengths from pepsinized human collagen [38], implying that regions of collagen with a less acidic nature were preferentially preserved in the fossils.