General Purification

Astrea Bioseparations Ltd (Astrea) have a range of high performance Ion Exchange and Hydrophobic Interaction Adsorbents which can be used in in combination with our Affinity adsorbents to produce highly pure proteins.

What is Ion Exchange Chromatography?

Ion Exchange (IEX) chromatography is used to separate proteins based on their net charge at a particular pH. A protein is positively charged when the pH is below the pI (isoelectric point) of the protein and is negatively charged when the pH is above the pI of the protein. IEX chromatography separates proteins by a reversible interaction between the charged protein and an oppositely charged adsorbent.

Astrea Bioseparations IEX range includes DEAE, CM, Q and SP adsorbents.

What is Hydrophobic Interaction Chromatography?

Hydrophobic Interaction Chromatography (HIC) is used to separate proteins based on relative hydrophobicity.  Interactions between hydrophobic groups in water are promoted by the presence of water structuring salts, and at high ionic strengths, hydrophobic residues on the surface of a protein associate strongly with other hydrophobic species (the ‘’salting-out’’ effect).  At very high ionic strengths protein precipitation occurs.  However, at intermediate ionic strengths, proteins can be adsorbed from solution onto hydrophobic surfaces.  This adsorption is reversible, and elution is achieved by simply lowering the ionic strength.  Consequently, HIC is particularly useful for the purification from high ionic strength biological extracts since binding is performed in the presence of salt and elution in the absence of salt.  The technique may be applied to the purification of most soluble proteins.

Astrea Bioseparations HIC range includes both Phenyl and Octyl adsorbent.