Membrane Proteins Purification

After the suitable detergent or other technologies have been used to solubilize and stabilize membrane proteins from the membranes, it is time to purify membrane proteins. The methods of protein purification mainly take advantage of the similarities and differences between different proteins. Specifically speaking, non-protein substances can be removed according to the similarity between proteins, and then target proteins can be separated according to the difference of proteins. Although membrane protein purification is often challenging, Alfa Chemistry is committed to optimizing and solving the challenge in the preparation process of membrane proteins. We can utilize a variety of technologies to help you isolate and purify the specific membrane proteins of your interest.

Purification Technologies

Multiple chromatographic techniques including ion exchange, affinity, gel filtration and chromatofocusing will be adopted by Alfa Chemistry in the purification of membrane proteins.

Fig. 1 The theory of ion-exchange chromatography.

Ion exchange chromatography

Ion exchange chromatography uses bio-macromolecules such as derivatives of cellulose or crosslinked dextran gels as carriers, in which the carriers have positive or negative charge at a certain pH value. When the protein molecules to be separated pass through the carrier, the protein molecules can be separated and purified through ion exchange. It is one of the common methods for separation and purification of proteins.

Affinity chromatography

Fig. 2 The theory of affinity chromatography.

Affinity chromatography is an isolation and purification method based on the characteristics of the reversible binding properties of proteins and some molecules (such as ligand). As the protein solution passes through the chromatographic column, the receptors that can interact with the affinity ligands are bound to the adsorbent, while the unrelated components that are not adsorbed can follow the effluent through the column, thus separating the purifying proteins.

In general, affinity chromatography is by far the most useful and successfully applied method for purification of integral membrane proteins and can be used at various purification steps. At Alfa Chemistry, several affinity chromatographies that are commonly used in membrane protein purification, including bare lectin-affinity chromatography, ligand-affinity chromatography and antibody-affinity chromatography.

Fig. 3 The theory of gel filtration chromatography.

Gel filtration chromatography

Gel filtration chromatography is also known as molecular sieve or size-exclusion chromatography. The technology is based on that the porous carriers have different resistance to protein molecules of different sizes and shapes to purify and separate proteins. Gel filtration chromatography is often used in the final stage of separation of membrane proteins because samples are continuously diluted during elution.

Chromatofocusing

Chromatofocusing is a high resolution column chromatography method that separates and purifies proteins according to isoelectric point. It combines the high capacity of anion-exchange chromatography with the excellent resolution of isoelectric focusing techniques.

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