Protein expression services allow researchers to obtain significant quantities of recombinant proteins. Using advanced molecular cloning and genomics technologies, a gene can be inserted into a host cell and then expressed as a recombinant protein. This can be done in a variety of host systems including bacteria, baculovirus-infected insect cells, yeast and mammalian cells. The recombinant protein can then be purified for further analysis or used in downstream applications.

The recombinant protein expression services can also be fused to an epitope tag (i.e. GST, His, Fc, etc) which allows the protein to be detected by antibody and/or cleaved by a protease to release a soluble fraction of the protein. The protein can be tagged on the N- or C-terminus.

Protein Expression Services Explained: Choosing the Right Platform for Your Project

In most cases, the recombinant protein will be produced in bacteria. The most commonly used host system is E. coli which can be easily grown in standard laboratory conditions and the protein expression can be induced with a DNA plasmid. The plasmid can be isolated from the bacterial cell and then purified using a specialized plasmid purification kit.

CHO or HEK293 cells can be cultivated in high density (1×106 cells/ml) suspension cultures and transfected with a mammalian expression plasmid. A 100 ml culture of the transfected cells or conditioned media (for secreted proteins) will be harvested at 24, 48, 72 and 96 hours post-boost to evaluate the integrity, stability, solubility and optimum yield of the protein(s). The expression process can be optimized by conducting shake flask and 1-L fermentor screening experiments to select high-yield and high-quality candidate production strains.