Protein purification can be a costly and time-consuming process in the manufacture of biomolecules. Whether from a tissue or by overexpression in a model organism, e.g. bacteria, yeast or mammalian cells in culture. One of the goals of the process is to obtain the highest functional yield of proteins while minimizing contaminants.

Many factors can affect the quality and process results for protein purification. Therefore, to obtain the desired yield and purity, optimization and selectivity of proteins from crude cell lysates is imperative, as well as ensuring proper solution conditions at each step. A good buffer environment is required to avoid pH changes that may affect protein solubility, function, and folding. Some of the characteristics of a good buffer are: chemical stability, water solubility, high capacity at the expected pH, and compatibility with analytical and experimental applications.

Despite quality assessment of protein sample purity and integrity and different techniques to detect potential contaminants, impurities and low-amount degradation products can go undetected, especially in low-concentration samples or during optimization phases where small aliquots are analyzed.

To preserve yield, it is important to differentiate between impurities that need to be completely removed and those that can be reduced to acceptable levels, as different types of material will contain different impurities. In any case, the quality of the final product should never be compromised. A good practice is to work with highly efficient techniques in the early stages of the process to capture the product and reduce the contaminant content, then continue to work with higher selectivity in later steps for optimal separation. Some other basic rules include: Work quickly, remove protease to keep the target protein active, minimize sample handling, combine techniques with complementary selectivity, work from large beads to small beads.

At CBL we have extensive practical experience and expertise in immunoaffinity protein purification.