Dialysis and concentration of protein solutions.

Conventional dialysis separates small molecules from large molecules by allowing diffusion of only the small molecules through selectively permeable membranes. Dialysis is usually used to change the salt (small-molecule) composition of a macromolecule-containing solution. This unit describes dialysis of large- and small-volume samples using cellulose membranes with pore sizes designed to exclude molecules above a selected molecular weight. A support protocol describes preparation of membranes for dialysis and discusses issues related to the selection of membranes including commercial kits.