Protein expression and purification services involve the creation of highly pure, stable and biologically active protein for a variety of downstream applications. The specific nature of these applications determines the purity level required, compatible buffer/storage conditions and quality control tests.

After a suitable custom rabbit polyclonal antibody system is selected (bacterial, insect, yeast or mammalian cells), your protein of interest must be expressed within that cell type. Depending on the exact type of protein you are working with, it may need to be solubilized in the cell culture medium or secreted from the cells.

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To solubilize proteins in a solution, they are often exposed to denaturing agents that denature and dissociate them into their individual monomer subunits. This allows them to be separated according to their molecular weight by a technique called polyacrylamide gel electrophoresis (PAGE). Sodium dodecyl sulfate is commonly used as this detergent because it not only denatures the proteins but also coats each protein with a negative charge so that they run towards the positive lead in the electric field during PAGE. A reducing agent that breaks disulfide bonds, such as dithiothreitol, is also often added to the sample before PAGE.

Alternatively, proteins can be solubilized in a high-ionic strength protein chromatography column using an amphiphilic resin that binds to the hydrophobic regions of the proteins. The protein chromatography column is then washed with multiple elution solutions that are designed to remove contaminants and product aggregates that have the opposite surface hydrophobicity of your target protein. The specific activity of the target protein is determined by dividing its total activity by the total amount of protein recovered after each elution step and multiplying it by 100.