Recombinant proteins physicochemical properties

Looking at the downstream processing of recombinant pharmaceutical proteins from different sources as a whole, there are more common steps than operations addressing expression system-specific problems or requirements. One of the most important common features is that a given end product must meet the same standards and specifications in terms of safety, quality, potency and efficacy, regardless of the production host. Furthermore, the physicochemical properties of such end products should be identical, so that the intrinsic features used for purification (affinity, hy-drophobicity etc.) are the same. Well-established procedures and protocols should therefore be utilized, and should be adapted to the special requirements of the source material only when absolutely necessary. This is particularly true in the case of pharmaceuticals, since the tendency in this field is to stick to established methods... 

Some polymers have been purified on the basis of their physicochemical properties. For example, silk-like polymers have been purified by taking advantage of their low solubility in aqueous medium (13). Elastin-like polymers (ELPs) have been purified by temperature cycling above and below their inverse temperature transition (Tt) (14). This technique has been extended to produce an ELP-tag that can be used to purify a number of recombinant proteins by temperature cycling, which may be faster and less expensive than affinity chromatography (15). 

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