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PROTEIN EXPRESSION AND PURIFICATION SERVICE

Recombinant proteins are used throughout the whole spectrum of biomedical research. Once you have large quantity of purified protein, you could conduct many downstream experiments, such as enzyme kinetics, functional and structural studies. We are pleased to offer our customers a high quality protein expression and purification service. We have the capacity to take your project directly from gene synthesis to protein expression, refolding and purification. We can optimize protein expression, maximize product yield, and ensure purity to serve every aspect of your research needs. 

EXPRESSION SYSTEMS 

The main systems for the expression of recombinant protein are prokaryotic and eukaryotic. Prokaryotic recombinant protein expression systems (E.Coli) have several advantages, including ease of culture, rapid cell growth and relatively simple purification procedures. However, most post-translational modifications are not added by bacteria, and most proteins become insoluble in inclusion bodies and are very difficult to recover as functional proteins. Eukaryotic systems for the expression of protein include yeast, baculovirus cells, and mammalian cells. Advantages of these systems include high levels of expression, no inclusion bodies, and intact post-translational modifications. The expression systems we offer include: 

  1. E.Coli Expression System: Escherichia coli (E. coli) is one of the most widely used hosts for the production of heterologous proteins. Its genetics are far better characterized than those of any other microorganism.
  2. Baculovirus Expression System: The Baculovirus insect cell expression system is widely used for the production of precisely matured, folded and processed recombinant proteins. In contrast to E. coli, insect cells are able to incorporate post-translational modifications. This unique tool usually yields high amounts of the target protein, making it highly cost effective in comparison to other eukaryotic expression systems.
  3. Mammalian Expression System: Mammalian cell lines (CHO, HEK 293 etc) are widely used for the production of recombinant glycoproteins (vaccines, enzymes) as well as hormones and immunobiologicals (antibodies, interleukins, lymphokines), as they have the advantage of full posttranslational modifications of the expressed protein.
  4. Yeast expression system: Available upon special request.
 

For E.Coli expression projects there are standard prices and they come in guaranteed packages of 1 mg, 5 mg and 15 mg of purified protein. In the case of the Baculovirus or Mammalian expression projects we start with a pilot study (please inquire about pricing) in order to analyze whether the expression would be high or low. Based on the results of the pilot study the pricing for the subsequent full-length project will be determined. After the pilot study you can choose whether to continue with the project, should you be satisfied with the price and pilot study results.

Projects can either be initiated from gene synthesis, or you can simply provide the constructs that you would like to express. At the end of the project, we deliver all of the products we guarantee (amount of protein or study results).

THINGS TO CONSIDER FOR YOUR PROJECT

  • Sequence Optimization: In highly expressed genes, a narrow set of codons is used and these codons correspond to the more abundant tRNA species. This minimizes the risk of tRNA depletion during translation. In fact, the codons in a gene may be true bottlenecks, especially in cases where foreign genes are expressed in a host in which the usage of codons in highly expressed genes does not resemble the usage of codons in the species from which the foreign gene originates. In such cases, it has been shown that substitution of rare codons in the introduced gene may increase the yield dramatically. In addition, replacement of rare codons might decrease the chance of misincorporation and protect the protein from premature turnover.
  • Expression System: In order to decide which host is most suitable the amount and the degree of purity of the product as well as its biological integrity and potential toxicity should be considered. For example, bacterial expression systems are not suitable if post-translational modification is required to produce a fully functional recombinant product.
  • Expression Vector: Once the host has been selected, many different vectors are available for consideration. However, as for the selection of a suitable host system, the final choice of vector should take into consideration the specific requirements of the application and will, of course, be influenced by the behaviour of the target protein.
  • Tag: As for the selection of host and vectors, the decision to use which tag must be made according to the needs of the specific application. The two most commonly used tags are glutathione S-transferase (GST tag) and 6 x histidine residues ((His)6 tag). 
 
Upon receiving your sequence information, the Bio Basic scientists will analyze the sequence to determine characteristics like molecular weight, pI, solubility, susceptibility to oxidation and hydrophobicity. Every protein is different, there is no standard way for protein expression and purification, and the protocols and strategies must be worked out for each individual protein and with its intended use in mind. Scientists at Bio Basic use their experience and expertise in purifying recombinant protein to best tailor the service for your research needs.

Contact your BaseClear account manager using our contact form to discuss your protein expression and purification project! 

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