Scientists at the Rensselaer Polytechnic Institute in New York have discovered how some proteins can withstand high temperatures and maintain their function while other similar structures fall apart.
Publishing their findings in the Proceedings of the National Academy of Sciences, the researchers compared the composition and structures of 15 closely-related proteins, which are all members of the thioredoxin family - these are present in all living things, from bacteria that survive in boiling hydrothermal ocean vents to those that can survive in freezing polar seas.
Nearly half of these were sequences of ancient proteins dating back more than 4 billion years, which were reconstructed using special genetic ‘archaeology’ techniques.
The team found that the difference in stability at high temperatures is mainly due to differences in how much energy is required to unfold them - reflecting the stability of the chemical and physical bonds within each protein’s structure.
Intriguingly, the scientists discovered that the ancient proteins unfolded more slowly than modern versions, in some cases 3,000 times more slowly, even though they fold up into their correct structures at the same rate. For example, in the case of two seemingly similar thioredoxins, one unfolded within seven seconds at high temperature, while another lasted for six hours.
The discovery could provide important clues for biological engineers designing enzymes or other protein molecules that can withstand the high temperatures needed for some industrial applications, suggesting that they should look back into ancient history in search of tomorrow’s new ideas.