The advantages of Medicilon protein expression service are short experiment period, low cost and high yield. Protein expression refers to a molecular biology technique that uses model organisms such as bacteria, yeast, animal cells or plant cells to express foreign gene proteins. It occupies a core position in genetic engineering technology.
Main methods: E. coli expression system, yeast expression system, insect cell expression system, mammalian cell expression system, plant cell expression system
Introduction of main expression systems:
- Prokaryotic expression system: The method of inserting the cloned gene into a suitable vector and introducing it into E. coli for expressing a large number of proteins is generally called prokaryotic expression. This method has applications in protein purification, localization, and functional analysis. Medicilon researchers have established a mature E. coli expression and purification service platform to provide expression and purification services including various recombinant proteins and their complexes in E. coli. service items:
Recombinant plasmid construction; Recombinant expression test; Soluble expression condition test; Small-scale protein expression and purification (2L medium culture product); Large-scale protein expression and purification (above 10L).
General procedure for prokaryotic expression: Obtain target gene = “Preparation of expression vector = “Insert target gene into expression vector (sequencing verification) = “Transform expression host bacteria = “Induction of target protein expression = “Analysis of expressed protein = “Amplification, Purification and further testing.
Advantages: Prokaryotic protein expression system is not only the most commonly used expression system, but also the most economical protein expression system. The prokaryotic protein expression system is represented by the E. coli expression system, which has the advantages of clear genetic background, low cost, high expression, and relatively simple separation and purification of expression products;
Disadvantages: mainly due to the lack of processing mechanisms after protein translation, such as disulfide bond formation, protein glycosylation and correct folding, the probability of obtaining biologically active proteins is small.
- Yeast expression system: As an emerging foreign protein expression system, the yeast expression system is getting more and more widely used in the field of genetic engineering due to the advantages of both prokaryotic and eukaryotic expression systems. The application of this system can be at a high level It expresses proteins and has the function of post-translational modification, so it is recognized as a powerful tool for expressing large-scale proteins. Medicilon researchers have established a mature yeast expression and purification service platform to provide high-quality recombinant protein expression and purification services in Pichia and Saccharomyces cerevisiae. service items: Construction of recombinant yeast expression plasmid; Electric transformation of recombinant plasmid; Recombinant expression screen; Small-scale protein expression and purification (2L medium culture product); Large-scale protein expression and purification (above 10L).
Advantages: The yeast protein expression system is represented by Pichia pastoris, which has the advantages of high expression, inducible, glycosylation mechanism close to higher eukaryotes, easy purification of secreted proteins, and easy realization of high-density fermentation.
Disadvantages: Some protein products are easily degraded, and the expression level is uncontrollable.
- Expression system of mammalian cells and insect cells: mammalian cells expressing foreign recombinant proteins can be transfected with plasmids and infected with viral vectors. The use of plasmid transfection to obtain stable transfected cells takes weeks or even months, while the use of viral expression systems can quickly infect cells and integrate foreign genes into viral vectors within a few days, especially suitable for large-scale expression. The target protein was detected in the product.
Advantages: the post-translational processing mechanism of the protein is closest to the natural form in the body, and the biological activity is easily retained.
Disadvantages: the expression level is usually low, the technical difficulty of establishing stable cell lines is difficult, and the production cost is high.
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