About 30% of all the protein found in mammals is collagen, making it the most abundant protein found in mammals. It is the main component of connective tissue and is found in muscles, tendons, ligaments and skin as well as in the cornea, cartilage, bone, blood vessels, the gut and intervertebral discs.
A collagen molecule can be about 300nm long and 1.5nm wide and is made up of 3 polypeptide chains in the structure of a left-handed helix. These helices twist together into a right-handed coil forming a triple helix which is stabilized by hydrogen bonds.
In each of the three polypeptide chains there is a regular arrangement of amino acids, often following the sequence Gly-Pro-X or Gly-X-Hyp where X is another amino acid.
Bio-archaeologists are excited about this because it is believed that protein can last in a useful form ten times longer than DNA. So, while DNA is useful in discoveries up to 100,000 years old, collagen could be used in identifying extinct animals up to 1,000,000 years old.
M. Buckley, N. Larkin, M. Collins. Mammoth and Mastodon collagen sequences; survival and utility. Geochimica et Cosmochimica Acta, 2011; 75 (7): 2007 DOI: 10.1016/j.gca.2011.01.022
- What is the general name given to the smaller units that make up a protein?
- Name the four elements found in all proteins.
- What is meant by the term polypeptide?
- Explain why proteins are considered to be biological polymers.
- What is a peptide bond?
- Amino acids are often represented by a three letter code. Give the name for each of the following amino acids:
- Draw a structure for each of the following tripeptides:
- Identify the peptide bond(s) in each of the tripeptides above.
- What is meant by each of the following terms with respect to proteins:
- primary structure
- secondary structure
- tertiary structure
- Describe the primary, secondary and tertiary structures for collagen.