Quantum Physics in Proteins

Artificial intelligence affords unprecedented insights into how biomolecules work

A new analytical technique is able to provide hitherto unattainable insights into the extremely rapid dynamics of biomolecules. The team of developers, led by Abbas Ourmazd from the University of Wisconsin–Milwaukee and Robin Santra from DESY, is presenting its clever combination of quantum physics and molecular biology in the scientific journal Nature. The scientists used the technique to track the way in which the photoactive yellow protein (PYP) undergoes changes in its structure in less than a trillionth of a second after being excited by light.

“In order to precisely understand biochemical processes in nature, such as photosynthesis in certain bacteria, it is important to know the detailed sequence of events,” Santra explains their underlying motivation. “When light strikes photoactive proteins, their spatial structure is altered, and this structural change determines what role a protein takes on in nature.” Until now, however, it has been almost impossible to track the exact sequence in which structural changes occur. Only the initial and final states of a molecule before and after a reaction can be determined and interpreted in theoretical terms. “But we don’t know exactly how the energy and shape changes in between the two,” says Santra. “It’s like seeing that someone has folded their hands, but you can’t see them interlacing their fingers to do so.”

Read more on the PETRAIII website

Image: Illustration of a quantum wave packet in close vicinity of a conical intersection between two potential energy surfaces. The wave packet represents the collective motion of multiple atoms in the photoactive yellow protein. A part of the wave packet moves through the intersection from one potential energy surface to the other, while the another part remains on the top surface, leading to a superposition of quantum states

Credit: DESY, Niels Breckwoldt