Facile Desalination from Protein Solution and Mutual Separation of Protein Mixture via Continuous Counter-current Foam Separation

The desalination of protein precipitates obtained after salting-out was performed by counter-current foam separation, a method developed in our laboratory. By supplying water as a washing liquid from the top of the column, NaCl was effectively removed from mixtures containing bovine serum albumin (BSA), cytochrome C (CytC), and lysozyme (LZM). In addition, the mutual separation of proteins was investigated using two ternary systems: NaCl/CytC/BSA and NaCl/LZM/BSA. Markedly high separation factors were achieved for BSA/CytC, and BSA/LZM, respectively. In the separation of BSA/LZM, an optimal washing liquid flow rate was observed. This optimal condition is attributed to the foam structure, in which a narrow bubble size distribution with a bubble diameter of approximately 5 mm ensured uniform flow of the washing liquid, thereby enhancing separation efficiency for the target.