Project information
Cryo-dynamics of pH responsive hairpin structure

Structural biology often relies on working at extremely low temperatures to “stop time” and capture detailed images of biological molecules. In methods such as cryo-electron microscopy and solid-state NMR, it is usually assumed that freezing preserves molecules exactly in the state they had in the cell or in solution under natural conditions. However, this assumption may not always be correct. The speed at which a sample is frozen, and the protective additives used to prevent ice formation, can themselves influence the molecular arrangement and even shift the balance between different structural states.

The goal of this project is to explore hyperquenching – an ultra-fast cooling process that requires no additives. This method could enable samples to be prepared in a form much closer to their natural state, providing a more faithful representation of biological structures.

As a model system, we use a short DNA hairpin that functions as a molecular ‘switch’ controlled by pH. At certain pH values, the molecule folds into a stable shape, while at others it remains unfolded. This behavior is ideal for testing because it can be tracked quantitatively at near-atomic resolution using solid-state NMR spectroscopy, and it directly reveals whether freezing conditions alter the equilibrium between folded and unfolded states.

This project will therefore provide not only new insight into the behavior of this particular DNA system, but also an important answer to a broader question: to what extent can we trust frozen biological samples to truly reflect the natural states they had in solution? If hyperquenching proves to give a more accurate picture, it could become a new standard for preparing biological samples in both fundamental research and applied biomedical science.