Drew Jordahl

Laser-Induced Rehydration of Cryo-Landed Proteins Restores Native Structure

Cryo-electron microscopy (cryo-EM) has become a widely used tool for solving protein structures, but
current limitations in sample preparation makes structural analysis impossible for many proteins of interest.
Using mass spectrometry (MS) as a sample preparation device, we deposit gas phase proteins onto a
cryogenically cooled grid for subsequent analysis with EM. Doing this solves the orientation bias and airwater
interface problems present with the commonly used plunge freezing method. However, new
challenges present themselves as gas phase proteins undergo structural changes limiting the biological
relevance of structures solved with this method. To overcome these imposed challenges, we use a 532nm
laser to rapidly melt and revitrify ice deposited on the cryo-EM grid to restore native protein structure and
have demonstrated its effectiveness with a model protein. This improvement paves a path forward for MS to
be a valuable sample preparation tool for the structural biology community.