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Recombinant human J-chain: fix the protein aggregations and yield maximize
El-Rashdy M Redwan1, Saleh M Matar, Ihab A Serour
1Protein Research, Department Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, New Borg El-Arab, Alexandria, 71783, Egypt. redwan1961@yahoo.com
Human Antibodies
|October 27, 2006
Summary
Researchers successfully produced a soluble joining (J) chain protein by mutating free cysteines to serine residues, overcoming aggregation issues and enabling large-scale production for immunoglobulin assembly studies.
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Engineering
Background:
- Polymeric immunoglobulins (IgA, IgM) require the joining (J) chain for assembly and transport.
- Previous models of J-chain folding exist, but its crystal structure is elusive due to protein aggregation caused by free thiol groups.
Purpose of the Study:
- To overcome J-chain aggregation problems and obtain a soluble protein for structural and functional studies.
- To develop a scalable production method for the recombinant J-chain protein.
Main Methods:
- Mutating cysteine residues to serine to eliminate free thiols.
- Expressing the modified J-chain in E. coli using a pET22b vector.
- Optimizing batch culture conditions and scaling up production in a 3-L bioreactor with automated process control.
Main Results:
- Mutation of cysteines to serine yielded a completely soluble J-chain protein (11.5 mg/l) migrating at 27 KDa on SDS-PAGE.
- Chemical blocking of free cysteines resulted in partially soluble proteins with altered structures.
- Optimized bioreactor cultivation achieved a biomass of 5.98 g/L after approximately 27 hours.
Conclusions:
- Mutating cysteines to serine is an effective strategy to produce soluble J-chain protein.
- The developed scalable production process enables high-yield recombinant J-chain production.
- This work facilitates further structural and functional investigations of the J-chain in immunoglobulin assembly.
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