Researchers observe the way proteins change between structures for the first time.

Biochemists from Oregon State University have achieved a fundamental discovery on protein structure that could shed some light on the way they fold. This discovery could allow scientists to better understand some important changes in protein structure – changes that seemed impossible to characterize due to the fact that these transitions were incredibly fleeting.

These changes are related to the way proteins change from one visible shape to another, and these changes occur in one trillionth of a second. It was known that these changes happened, and they had been simulated in computers, but the way they occurred hadn’t been observed ever before.

All proteins start out as single chains that fold quickly, going through many energy transitions. A correct folding is fundamental in the biological function that proteins serve; when this folding fails, many diseases can happen, such as Alzheimer’s.

Up until now, scientists had used X-ray crystallography in order to capture images of proteins in their stable forms, but it wasn’t known how exactly proteins switched from one form to another. These changes are brief and need molecular distortions that are extreme and hard to predict.

What these researchers found was that the stable forms adopted by some proteins actually contained parts that were trapped in the act of switching forms, similar to an insect trapped in amber.

"We discovered that some proteins were holding single building blocks in shapes that were supposed to be impossible to find in a stable form," said Andrew Karplus, the author on the study and professor of Biochemistry and Biophysics in the OSU College of Science.

"Apparently about one building block out of every 6,000 gets trapped in a highly unlikely shape that is like a single frame in a movie," Karplus said. "The set of these trapped residues taken together have basically allowed us to make a movie that shows how these special protein shape changes occur. And what this movie shows has real differences from what the computer simulations had predicted."

Researchers believe that the importance of these discoveries could take years to become evident, but it’s clear that proteins are fundamental on the processes of life, and this information has revealed details about protein folding in a way that hadn’t been thought possible before.

Sources: http://phys.org/news/2015-10-discovery-protein-window-basic-life.html
http://advances.sciencemag.org/content/1/9/e1501188.full