Gold nanoparticles as nucleation-inducing reagents for protein crystallization

Protein crystallization is a necessary but time-consuming and difficult step in structure determination by crystallography. The rate-limiting step of crystallization is nucleation, where protein monomers in solution cluster in an ordered fashion to form a stable nucleus. Here, we propose the use of gold nanoparticles to accelerate nucleation and enhance crystal formation. We tested whether gold nanoparticles can facilitate nucleation by interacting with target proteins and inducing favorable clustering. We used differently sized gold nanospheres and gold nanostars to crystallize hen egg-white lysozyme. Our results indicated that gold nanoparticles significantly increased the number of crystallization conditions (by about 20%). Spherical and larger gold particles were found to be more efficient. Furthermore, the use of gold nanoparticles did not have any adverse effect on data collection or structure determination. Our findings indicate that the use of nanoparticles as protein nucleation-inducing reagents can greatly accelerate structure determination by X-ray crystallography.