Refolding of the Alkali Denatured Bovine Beta-Lactoglobulin by the Synthetic ZnO Nanochaperone: A Useful Technique for Protein Renaturation.

Proteins undergo unfolding and subsequent denaturation by the alternation of physical parameters like pH and temperature or by the addition of salts and denaturants. Protein denaturation and misfolding make it nonfunctional or trigger protein aggregation. Owing to their size, shape, and surface charges, nanoparticles act as artificial chaperones by providing the scaffold for the favorable conformation that prevents protein aggregation and refolds the protein into its native functional form. In the present study, the structure of the unfolded bovine beta-lactoglobulin in an alkaline medium has been investigated and compared with the native protein at physiological pH. Further, this alkali-unfolded beta-lactoglobulin was refolded to its native-like structure by the gradual addition of synthesized ZnO nanoparticles, thus acting as an artificial chaperone. Applying multispectroscopic, DLS, and electron microscopy studies, we have investigated the structures and hydrodynamic radii of the native, unfolded, and refolded proteins. The hydrodynamic radii of the refolded protein were nearly identical to those of the native protein. Therefore, the refolded beta-lactoglobulin demonstrated the structure that is close to the native form.