How to choose a recombinant protein expression system: industry thinking from plasmid construction to quality control

Recombinant proteins are one of the basic tools in the field of biological reagents, in vitro diagnostics and antibody drug research and development.By introducing the target protein coding sequence into the host through genetic engineering, large-scale preparation can be achieved, and the risks of limited natural extraction sources and large differences between batches can be reduced.Faced with different application scenarios, companies need to balance the expression system, process route and quality standards.

Applicable boundaries of common expression systems

There is no universal scheme for the recombinant protein expression system, which requires a comprehensive judgment of protein structure, post-translational modification, use and cost.E. coli is fast-growing and low-cost, suitable for antigenic, enzymatic and cytokine fragments that do not require complex modification; yeast and insect cells have a certain expression efficiency and modification ability, suitable for some eukaryotic proteins; mammalian cells can provide glycosylation and folding in a near-natural state, which are often used to diagnose key antigens, receptors and treatment-related proteins; cell-free systems are suitable for toxic proteins, high-throughput rapid expression and special labeling scenarios.

Process control from genes to proteins

Stable recombinant protein feedstocks begin with sequence design and vector construction.Codon optimization, label selection, signal peptide design, and host adaptation can affect soluble expression levels and subsequent difficulty of purification.The fermentation or cell culture process needs to control the temperature, feeding, oxygen dissolution, induction timing and culture cycle; after harvesting, the host protein, nucleic acid and aggregates are removed through affinity, ion exchange, gel filtration and other steps.If histidine labels, GST labels are used in the process, label resection should also be evaluated according to the application requirements