Solvent-free liquid myoglobin

Water, essential to life… or is it?

Proteins are large biological molecules that are synonymous with living things. They allow us to convert food into energy, supply oxygen to our blood and muscles, and drive our immune systems.

 

It is the general understanding that since proteins have evolved in a water-rich environment, they are dependent on water to survive and function. Researchers at the University of Bristol have used the Circular Dichroism beamline (B23) at Diamond Light Source to challenge this dogma by showing that the oxygen-carrying protein myoglobin can refold in an environment that is almost completely devoid of water molecules.

 

Lead researcher on the project, Dr Adam Perriman from the University of Bristol, explains, “If a protein in water is heated to temperatures approaching the boiling point of water, the highly-organized 3D chain of amino acids will lose its structure and the protein will unfold (denature). This is part of the process that occurs when an egg is hard-boiled; the structures of the proteins in the egg unfold with temperature and stick together creating a solid. In this case, the process cannot be reversed, although there are many examples where cooling the protein results in refolding of the structure.”

A protein folds to assume its functional shape. It has been thought that water is essential to this process. But the Bristol team’s results, which were recently published in the journal Chemical Science, suggest that this isn’t necessarily the case.

“We were able to show that myoglobin can refold in an environment that is almost completely devoid of water molecules. We achieved this by attaching polymer molecules to the surface of the protein and then removing the water to give a viscous liquid, which when cooled from a temperature as high as 155°C refolded back to its original structure. We used beamline B23 at the Diamond synchrotron to track the refolding of the myoglobin structure and were astounded when we became aware of the extremely high thermal resistance of the new material.”

Dr Adam Perriman, University of Bristol