Salting Up and Salting Down of Bovine Serum Albumin Layers at the Air-Water Interface

Published

December 22, 2020

Author(s)

Guangcui Yuan, Paul A. Kienzle, Sushil K. Satija

Abstract

The surface adsorption of BSA in pure water and salted aqueous solutions was studied by neutron reflection. With contract match technique, the surface excess in null reflect water as a function of protein concentration was revealed. It is found that, in a concentration range of 0.2 ppm to 1000 ppm, without salts, the surface excess shows a profound peak at around 20 ppm; with salts, the surface excess increases steadily with the protein concentration. When the surface excess at a specific protein concentration is viewed, the introduce of sodium chloride causes either a salting-down effect --- surface adsorption decline or a salting-up effect --- surface adsorption enhance, depending on the protein concentration. Salting-up effect is observed at the low ( 1 ppm) and high ( 1000 ppm) concentration ends , and salting-down effect dominates the intermediate concentration range. The salting-up or salting-down behaviors is found to be directly related to the solution pH, which is not a constant but varies with protein - protein interaction (here, bulk protein concentration).When the solution pH is shifted toward to the isoelectric point by adding salts, surface adsorption enhances; When the solution pH is shifted away from the isoelectric point by adding salts, surface adsorption declines.

Citation

Langmuir

Volume

36

Issue

50

Pub Type

Journals

Keywords

Bovine Serum Albumin, surface adsorption, neutron reflection, salt effects

Citation

Yuan, G. , Kienzle, P. and Satija, S. (2020), Salting Up and Salting Down of Bovine Serum Albumin Layers at the Air-Water Interface, Langmuir (Accessed April 16, 2024)