Applications of Protein Purification

Protein purification has many uses in drug delivery, tissue engineering and biointerface science. Elastin-like peptides can be purified to separate a single type of protein from a complex mixture. Due to the increased demand for drug delivery and tissue engineering of peptide-based biomaterials, efficient protein purification techniques must be used. The four approaches described in this report are affinity chromatography, reverse conversion cycle (ITC) based on centrifugation, reverse conversion cycle based on microfiltration, and finally protein purification with self-cleavage purification tag.

Ion exchange chromatography, named after exchangeable counterions, is a method for protein purification of ionizable molecules. Ionizing molecules are separated based on nonspecific electrostatic interactions between their charged groups and oppositely charged molecules attached to the solid support matrix, thereby retarding the ionizing molecules that interact more strongly with the solid phase . The net charge of each type of ionized molecule and its affinity for the matrix will vary depending on the number of charged groups, the charge of each group, and the nature of the molecule interacting with the charged solid phase matrix. These differences make it possible to separate various molecular types by ion exchange chromatography. In a typical protein purification using ion exchange chromatography, a mixture of many proteins (eg in mammalian cell culture) from a host cell is subjected to an ion exchange column.

This three-step purification strategy is most commonly used for protein purification. Ion exchange chromatography is used to capture proteins, hydrophobic interaction chromatography is used for intermediate purification, and gel filtration (GF) is used for protein polishing steps. The purpose of using this three step purification method is to obtain high purity form of the protein which can be used for crystallization and structure determination. The anion exchange column array is first screened to help select the optimum medium, then the larger column is selected and used to optimize the capture step. Deacetoxycephalosporin C synthase Sepharose XL is most commonly used to capture oxygen sensitive enzymes. It is suitable for trapping. Step elution was used at high flow rate to facilitate protein purification of the recombinase deacetoxy cephalosporin C synthase. This process can be used to capture potentially unstable compounds.

Novel methods for purifying recombinant proteins expressed as proteins or particles are described herein. During this purification, the protein is purified by hydrophobic interaction. This protein step interaction improves recovery and purity from 15% to 80%. Further purified proteins have utility in vaccines and pharmaceuticals. It is also a common practice to use a variety of cellular substrates to propagate the virus to produce viral antigens. During this process, the cells proliferate in large amounts and then "infect" them with the desired virus to promote viral growth. Alternatively, transfected cells can be cultured.