Spectroscopic study of gamma irradiation effect on the molecular structure of bovine serum albumin

Abstract

The effect of gamma radiation on the molecular structure, size distribution and surface charge of bovine serum albumin (BSA) was studied by spectroscopic techniques. The first structure of non-irradiated and irradiated BSA were investigated by UV-Vis spectroscopy and electrophoresis (SDS– PAGE). Additionally, the secondary and tertiary structural changes of BSA were studied by circular dichroism (CD) and fluorescence spectroscopy, respectively. Dynamic light scattering (DLS) and electrophoretic light scattering (ELS) was used for clarify of size and surface charge of BSA. The results indicate that the first structure of BSA is preserved, while the secondary and tertiary structures have changed significantly. The result of CD studies shows an 8% decrease in α-helix and an increase in other secondary structures for irradiated BSA in comparison to non-irradiated ones. Moreover, DLS and ELS displayed the decrease in the size and surface charge of irradiated BSA. The aggregation of irradiated BSA was also confirmed by fluorescence spectroscopy. The ELS results as an additional data confirm the aggregation of protein. The results demonstrate that doses close to therapeutic ones can lead to structural changes in macromolecules as well as the aggregation of polypeptide chain but without the fragmentation.