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Bacterial expression

      E.coli is the preferential one of bacterial systems for recombinant protein production and large scale fermentation as its advantages including fast rate of reproduction, ease of culture, and rich knowledge about its genetics. With abundant experience of soluble protein expression and production and protein refolding, TGpeptide can provide you high-quality expression service.

  • E.coli Protein Expression Service Details

    Service procedures



    1.Gene synthesis and codon optimization (optional)

    1-2 weeks

    2.Vector construction

    clone cDNA into expression vector

    plasmid sequencing

    large-scale plasmid preparation

    1-2 weeks

    3.Expression evaluation

    transformation into proper strain

    small-batch fermentation

    SDS-PAGE analysis to evaluate protein expression

    1-2 weeks

    4.Protein expression and purification

    fermentation based on expression evaluation

    protein purification   soluble expression-affinity purification   inclusion body expression-refolding

    SDS-PAGE and UV analysis

    2-3 weeks


    Sequencing report

    Expression evaluation result

    Purified protein

    SDS-PAGE report


  • Endotoxin content testing service

       TGpeptide provide endotoxin content testing service. Endotoxins or LPS are cell membrane components of Gram-negative bacteria (such as E. coli). A single E. coli cell contains about 2 million LPS molecules. At the stage of actively growing, E.coli cell sheds small amounts of endotoxins into its surroundings, however, large amounts can be released while it dies.

    Here are endotoxin content requirements for different experiments in following list:


    Endotoxin content requirement

    Vitro enzyme activity experiment


    Production for antigen


    Vitro cell culture


    Other animal vivo experiment


    Endotoxin Detection

       The detection of endotoxin performs before and after endotoxin removal. The primary methods can be divided into qualitative (LAL gel-clot assay) or quantitative (LAL turbidimetric assay and LAL chromogenic assay).

    Normal standards of endotoxin in different fields:

    Application feild

    Endotoxin standard


    1 million EU/ml

    Running water

    10-100 EU/ml

    Biologic pharmacy

    <0.01 EU/ml

    Intrathecal injection drugs

    0.2 EU/kg

    Non-intrathecal injection drugs

    <5 EU/kg

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