Protein disulphide isomerase-induced refolding of sonochemically prepared Ribonuclease A microspheres

摘要

The present communication describes for the first time the development of Ribonuclease A ( RNase A) microspheres using the sonochemical method followed by an enzymatic treatment with protein disulphide isomerase ( PDI). Ultrasound application induced changes on the protein physicochemical and biological properties: the enzymatic activity of RNase A was decreased in 35% and the free thiol groups content was significantly increased, probably due to the breakage of protein disulphide bonds and assembly of RNase A monomers. The deconvolution of amide I band, from Fourier Transform Infrared Spectroscopy, showed that the secondary structure of RNase A was slightly changed after microspherization. The PDI application on microspheres promoted the recovery of RNase A biological activity and induced the release of active protein into solution in its native state. These results were promoted by different states of PDI active site: oxidized and reduced, respectively. The PDI aptitude to catalyze the refolding of a protein substrate in the form of spheres is here reported. (C) 2012 Elsevier B.V