Nanoparticles Guide Protein Folding

Coated gold nanoparticles can help denatured proteins refold properly, according to a study (Chem. Commun., DOI: 10.1039/b805242e). The material mimics natural “chaperones” such as the proteins GroEL and GroES that help misfolded proteins to refold properly by preventing them from aggregating. Chemistry professor Vincent M. Rotello and grad student Mrinmoy De at the University of Massachusetts, Amherst, devised gold nanoparticles coated with 2-(10-mercaptodecyl)malonic acid and used the synthetic chaperones to refold thermally denatured proteins. “The use of nanoparticles as artificial chaperones is intriguing because the surface properties of the nanoparticles can be tailored in diverse ways,” says Samuel H. Gellman of the University of Wisconsin, Madison. “It will be very interesting to see whether this technique can be used to refold proteins from chemically denatured states, as is often required for biotechnological applications.” In Rotello’s method, the nanoparticles prevent aggregation of unfolded proteins by binding to positively charged residues. Removing the nanoparticles by increasing the salt concentration of the solution frees the proteins to refold. Activity assays and circular dichroism spectroscopy have shown that the proteins refold into nearly native conformations.