Aqueous Two-phase System - Advantages

Advantages

ABS is an excellent method to employ for the extraction of proteins/enzymes and other labile biomolecules from crude cell extracts or other mixtures. Most often, this technique is employed in enzyme technology during industrial or laboratory production of enzymes.

• They provide mild conditions that do not harm or denature unstable/labile biomolecules
• The interfacial stress (at the interface between the two layers) is far lower (400-fold less) than water-organic solvent systems used for solvent extraction, causing less damage to the molecule to be extracted
• The polymer layer stabilizes the extracted protein molecules, favouring a higher concentration of the desired protein in one of the layers, resulting in an effective extraction
• Specialised systems may be developed (by varying factors such as temperature, degree of polymerisation, presence of certain ions etc. ) to favour the enrichment of a specific compound, or class of compounds, into one of the two phases. They are sometimes used simultaneously with ion-exchange resins for better extraction
• Separation of the phases and the partitioning of the compounds occurs rapidly. This allows the extraction of the desired molecule before endogenous proteases can degrade them.
• These systems are amenable to scale-ups, from laboratory-sized setups to those that can handle the requirements of industrial production. They may be employed in continuous protein-extraction processes.

Specificity may be further increased by tagging ligands specific to the desired enzyme, onto the polymer. This results in a preferential binding of the enzyme to the polymer, increasing the effectiveness of the extraction.

One major disadvantage, however, is the cost of materials involved, namely high-purity dextrans employed for the purpose. However, other low-cost alternatives such as less refined dextrans, hydroxypropyl starch derivatives and high-salt solutions are also available.