Protein Case Studies: E. coli cell expression system
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Protein requirement:
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No tag, refolding of insoluble protein, high purity >98% by SEC-HPLC, endotoxin <50EU/mg
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Strategy:
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Inclusion body solubilization
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Refolding optimization
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No tag purification via IEX purification
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Endotoxin removal: inclusion body washing, Q Sepharose FF column, endotoxin removal beads
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Turnaround time: 6 weeks
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Deliverables:
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20mg no-tag protein
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Purity >98%
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Endotoxin <50EU/mg
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Data
No tag, refolded and active cytokine mutant:
Human Heterodimer:
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Protein requirements:
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50mg, endotoxin level < 1EU/ug, > 90% SEC-HPLC purity
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Strategy:
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His-tagged S100A8 (10.8kDa) and tag-free S100A9 (13.2kDa)
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Dimer formation and purification by Ni-NTA column
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Deliverables:
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50 mg S100A8/S100A9 heterodimer
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Purity >90% by reducing SDA-PAGE and SEC-HPLC
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Endotoxin < 1EU/ug
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Data
High-throughput production
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Protein requirements:
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Over 1000 non-commercially available antigen proteins
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High yield, high purity, soluble proteins with no extra amino acid
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100 proteins/month
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Deliverables:
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>2mg tag-free soluble proteins at 90% purity
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Conc.>0.5mg/ml required for immunization
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High-throughput production process