Dinosaur peptide sequence positions were mapped on the two dimensional human collagen fibril D-period schematic³³.

<p>Dinosaur peptide sequence positions were mapped on the two dimensional human collagen fibril D-period schematic³³.</p

<i>Tyrannosaurus rex</i> femur (MOR 1125) from which demineralized matrix (insets; bars, 20 <b>µ</b>m) and peptides were obtained.

<p>Courtesy Museum of the Rockies.</p

Number of Acidic Residues.

<p><b><u>Chemical characteristics of fossil peptides.</u></b> 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 (<i>bolded, underlined</i>) in the peptides was lower than predicted for “average” peptides of comparable lengths from pepsinized human collagen <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020381#pone.0020381-Miller1" target="_blank">[38]</a>, implying that regions of collagen with a less acidic nature were preferentially preserved in the fossils.</p

X-ray diffraction model of the rat collagen microfibril <i>in situ</i>; Integrins, predominant cell-binding site; MMP, matrix metalloproteinase cleavage site; FN, fibronectin binding site; decoron, decorin proteoglycan core protein binding sites; putative cell and matrix interaction domains³⁵.

<p>X-ray diffraction model of the rat collagen microfibril <i>in situ</i>; Integrins, predominant cell-binding site; MMP, matrix metalloproteinase cleavage site; FN, fibronectin binding site; decoron, decorin proteoglycan core protein binding sites; putative cell and matrix interaction domains³⁵.</p

The collagen fibril (A) is composed of triple-helical monomers that polymerize in an overlapping fashion (B), and are derived from proteolysis of the soluble procollagen precursor (C).

<p>Fibrils appear as periodic banded structures by electron microscopy; one D-period (expanded two-dimensional view of 67 nm segment of microfibril, box) contains the complete collagen sequence from elements of five monomers and includes an overlap and gap zone; arrow, left border of overlap zone. Image of the X-ray diffraction-derived fibril subunit structure: the microfibril (D) shows aggregates of five triple-helical, rope-like monomers; magnified view shows triple helix containing three peptide chains (two α1 and one α2 chains) (E). Many thousands of microfibrils polymerize and cross-link to form cable-like collagen fibrils of vertebrates. Modified from original research <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0020381#pone.0020381-Sweeney1" target="_blank">[33]</a>.</p

Arrangement of collagen I α1 (top), α2 (middle) and collagen III α1 (bottom) chains demonstrates approximate alignment of charge across all three molecules in the D-period.

<p>Arrangement of collagen I α1 (top), α2 (middle) and collagen III α1 (bottom) chains demonstrates approximate alignment of charge across all three molecules in the D-period.</p

Arrangement of five overlapping collagen III α1 chains in the fibril D-period with overlap and gap zone indicated.

<p>Arrangement of five overlapping collagen III α1 chains in the fibril D-period with overlap and gap zone indicated.</p

Missense mutation distribution in collagen III.

<p>Missense mutation frequency along the residues of the collagen III chain. This demonstrates the non-random distribution of variation.</p

Major structural features and ligand binding sites for collagen III.

<p>Major structural features and ligand binding sites for collagen III.</p