Miscellaneous methods in affinity
A critical element of modern process biotechnology is the separation and purification of the target product from a fermentation broth or cell rupture supernatant. As it represents the major manufacturing cost, competitive advantage in production will depend not only on innovations in molecular biology sciences but also on innovation and optimization of separation and down-stream processes. The recent trend in bioseparations is to use affinity technology in the initial steps of the purification process allowing overall reduction in working volumes and thereby processing costs (Sii and Sadana, 1991). Affinity ligand to be used at an early stage of the purification protocol must be resistant to chemical and biological degradation, since the conditions used in the initial stages are much harsher than those used in the later stages. Low molecular weight, group specific ligands, the reactive triazine dyes included, are highly stable and are, therefore, favoured in such applications (Kaul and Mattiasson, 1992).