Fig. 2 in Protein sequences from mastodon and Tyrannosaurus rex revealed by mass spectrometry

Fig. 2. Collagen peptide sequences unique to extinct mastodon identified by LC/MS/MS. (A) The four collagen altl peptide sequences found by the approach that are unique to ancient mastodon. Xcorr (cross-correlation score) and Sp (preliminary score) represent the scores resulting from database searching against protein databases using Sequest. The asterisk represents the hydroxylation site after the posttranslationally modified residue. (B) An example of the experimental MS/MS spectrum of a doubly charged tryptic peptide for the collagen altl peptide sequence GSEGPQGTR from the LC/MS/MS analysis of mastodon fossilized bone extract identified from a Sequest search against a theoretical collagen protein database. (C) The synthetic version of the same peptide sequence. All major ions from the experimental spectrum align very well with the ions from the synthetic version, validating the sequence.Published as part of John M. Asara, Mary H. Schweitzer, Lisa M. Freimark, Matthew Phillips & Lewis C. Cantley, 2007, Protein sequences from mastodon and Tyrannosaurus rex revealed by mass spectrometry, pp. 280-284 in Science 316 (5822) on page 282, DOI: 10.1126/science.1137614, http://zenodo.org/record/374443