Effects of coexisting Na+ on the reentrant condensation of bovine serum albumin induced by Y3+ in aqueous media

Abstract

In an aqueous solution, certain charged proteins, which can be seen as macroions, often undergo reentrant condensation in the presence of salt. These macroions aggregate upon adding salt at a specific concentration, and further addition of salt leads to the dissociation of the aggregates. For bovine serum albumin (BSA), it has found that the reentrant phenomenon is caused by YCl3 [Zhang et al. 2008]. Fujihara and Akiyama have theoretically predicted that the attractive interaction between like-charged macroions induced by coexisting multivalent ions such as Y3+ is weakened by the addition of monovalent ions such as Na+ [Fujihara et al.2014]. In this paper, the impact of Na+ on the reentrant condensation of BSA in aqueous media is investigated by static light scattering (SLS) measurements. The phase diagram for the reentrant condensation of BSA reveals that the sedimentation range becomes narrow when Na+ is co-added, indicating that the coexistence of monovalent ions suppresses the attractive interaction between BSA induced by Y3+.