Physico-chemical boundaries in the continuous and one-step discontinuous affinity-chromatographic isolation of proteins

From a physico-chemical point of view, affinity chromatography has no unamb iguous definition. It is generally understood as the one-step chromatograph ic isolation of a protein from a biological sample. For such processes the protein recovery and the adsorption capacity for a given adsorption time is limited by static and dynamic physico-chemical properties of the system, T he protein recovery is limited by the ratio of the static capacity, n(s) an d the dissociation constant, K, for the interaction with the immobilized bi nding site. The limits of these quantities for 90% and 99% protein recovery were estimated. The residence time required to reach 90% of the adsorptive capacity of an adsorbent is a function of the above static properties, the pore-diffusion coefficient, D-p, and the diffusion distance in the adsorbe nt. It was estimated and was found to correlate well with experimental data . The one-step discontinuous or continuous chromatographic isolation of one p rotein from a biological sample by means of adsorbents that separate with r espect to different properties is reviewed. This is only possible with sele ctive specific adsorbents and, in special cases, also with bifunctional ads orbents that use hydrophobic interactions for the adsorption, and electrost atic repulsion for the desorption. (C) 2001 Elsevier Science B.V. All right s reserved.