The bonds of most proteins break after around 500 years, but collagen has been found preserved for nearly 200m years. MIT researchers think the reason lies in its triple helix structure.
Collagen is an abundant protein in animals and its ability to survive for long periods of time has puzzled researchers – until now.
A study at MIT looked at collagen and its resistance to time – the protein has been found in a preserved form on dinosaur fossils that are nearly 200m years old, while the normal bonds that hold protein bonds together usually last for around 500 years.
These researchers have been studying this particular protein for the past 25 years to understand why it is so stable. They believe the answer lies in how collagen strands form into a tough triple helix, preventing the peptide bonds that hold it together from breaking down.
“Collagen is the scaffold that holds us together,” said MIT’s Prof Ronald Raines says. “What makes the collagen protein so stable, and such a good choice for this scaffold, is that unlike most proteins, it’s fibrous.”
A water-resistant shield
Collagen accounts for around 30pc of your body’s protein and provides support and strength to bones, muscles and connective tissue. Like other types of protein, it is held together by chemical bonds – peptide bonds, which eventually get broken down by water molecules.
But collagen is structured in such as a way that water molecules are unable to get into the structure to disrupt the bond.
To test this, Raines and his team created two mimic versions of collagen – one that formed the normal triple helix structure and another where the angles of the peptide bonds are rotated into a different form. These two forms are referred to as trans and cis, respectively.
The researchers found that the trans form of collagen did not allow water to attack the bond, while water was able to break the bonds in the cis form.
“Collagen is all triple helices, from one end to the other,” Raines said. “There’s no weak link, and that’s why I think it has survived.”
There are other theories as to how collagen was found preserved for so long. One theory is that the dinosaur bones were so dehydrated that no water could reach the peptide bonds.
“I can’t discount the contributions from other factors, but 200m years is a long time, and I think you need something at the molecular level, at the atomic level in order to explain it,” Raines said.
In 2017, research from the University of Galway suggested that Parkinson’s disease could be treated by using a collagen brain matrix.
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