Custom Recombinant Protein

• • Comparison between different protein expression systems:

  Host	E.coli	Insect Cells	Mammalian Cells
  Type	Prokaryotic Expression	Eukaryotic Expression	Eukaryotic Expression
  Culture Density	High	High	Medium
  Culture Time	Short(1-2 days)	Medium(2-4 days)	Long(5-7 days)
  Protein Folding	Limited	Yes	Yes
  Post-translational Modification	No	Glycosylation, Phosphorylation	Glycosylation, Phosphorylation
  Suitable Proteins	Low molecular weight protein	Secretory and intracellular protein	Secretory protein
  Cost	Low	High	High
  Expressed Cells	BL21（DE3）, Rosetta…	Sf9，Sf21, High-five	HEK293, CHO

• • Custom Protein Services:

  

1. Prokaryotic protein expression services(E.Coli)

E.coli expression system is the widely used and cost-effective protein expression system. E.coli is featured with clear genetic background, rapid cell proliferation, simple culture, high expression level, strong anti-pollution etc.

Some limitations are also found in E.coli expression system, e.g. overexpression induced inclusion body, high level endotoxin, unsuitable for protein expression including post-translational modification, glycosylation and amidation.

Prokaryotic protein expression system is more suitable for expressing protein with low molecular weight and less modification. FineTest provides one-stop services to satisfy customers’ different requirements, covering codon optimization, gene synthesis, expression and purification, removal of endotoxin.

Service Items	Service Checklist	Service Timeline
Gene Synthesis	Codon optimization, expression vector construction, sequencing, plasmid preparation	1-2 weeks
Protein Expression	Solubility analysis, expression condition optimization	1 week
Protein Purification	Soluble protein purification, renaturation of inclusion bodies, QC Validation	1-2 weeks
Project Delivery	Protein sample purification, COA	Total: 3-4 weeks

2. Mammalian Transient Protein Expression Services

Mammalian cell expression system can perform complex post-translational modification, including glycosylation, phosphorylation and acetylation etc. Thus, expressed recombinant proteins are closer to conformation of native protein, showing higher biological activity and stability.

Transient expression system is featured with easy operation and short experimental cycle, obtaining a few recombinant proteins in the shorter period.

Our transient expression in mammalian cells mainly chooses HEK293 and CHO cells as host, offering flexible services to satisfy different custom requirements, such as tag removal, endotoxin removal etc. We have self-developed cell transfection technology and reagent formula. Thus, better products and services can be offered to customers in a cost-effective way.

Service Items	Service Checklist	Service Timeline
Gene Synthesis	Codon optimization, expression vector construction, sequencing, plasmid preparation	1-2 weeks
Protein Expression and Purification	Transiently transfected HEK293/CHO cell, protein purification, QC validation	2-3 weeks
Project Delivery	Protein sample purification, COA	Total: 3-5 weeks

3. Baculovirus Insect Cell Expression Services

Baculovirus insect cell expression system can efficiently express exogenous genes. The expression efficiency for larger gene segments is more higher. Insect cells have the post-translational modification ability similar to mammalian cells, producing recombinant proteins with the biological activity similar to native proteins.

FineTest has rich experience in baculovirus insect cell expression. The high titer of virus packaging technology is especially suitable for expressing some virus or toxic proteins.

Service Items	Service Checklist	Service Timeline
Gene Synthesis	Codon optimization, expression vector construction, sequencing, plasmid preparation	2 weeks
Virus Packaging and Amplification	Virus packaging and amplification	2 weeks
Protein Expression and Purification	virus infection, protein purification, QC validation	2-3 weeks
Project Delivery	Protein sample purification, COA	Total: 6-7 weeks