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Many proteins are very difficult to produce in heterologous expression systems and a lot of factors may contribute to this problem. 

A frequent problem encountered is that it can often be challenging for a foreign host to correctly fold a protein it does not normally produce e.g. expression of a protein originating from a higher eukaryote in bacteria where factors such as codon usage, translation rate and redox potential are significantly different. Furthermore, inherent properties of the target protein may present challenges for the expression host. An example of this is where a protein having multiple membrane spanning domains might not properly insert into membrane bilayers of the heterologous host or a protein might not be expressed in a soluble form. 


Finally, many proteins require post-translational modifications (e.g. phosphorylation, glycosylation, etc.) that are not present or significantly different from expression system to expression system.

There is therefore, no single solution for the recombinant expression of all classes of difficult proteins. Instead, specific solutions can be systematically determined for each protein that aim to increase the chances of success. For microbial expression systems, these solutions often come in the form of unique host strains complemented with optimized protein-specific expression parameters.

Common problems encountered when expressing proteins in heterologous expression systems using non-optimized parameters  include:

  • Partial or complete degradation of the recombinant protein

  • Poor solubility

  • Poor yields

  • Denaturation or poor activity

  • High basal expression leading to poor viability of expressing cells, etc.


At Gemini Biosciences, we can perform optimization assays using your protein expression construct to determine the best system and experimental parameters that will provide the highest yields and solubility of the recombinant protein in your expression system by using our automated protein expression optimization system. We will test for expression under various experimental conditions including cell strains, induction conditions, culture media, etc.


We also offer expression vector optimization, which includes codon optimization for the expression system and production of a set of vectors with different promoters, ribosome binding sites and fusion tags e.g. affinity, fluorescence, solubility, secretion, etc or combinations thereof.

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