The quality control platform developed by Xpress Biologics includes a large range of equipment / techniques dedicated to the characterization of the purified material:
- ready-to-use methods: SDS-PAGE, AGE, IEF, µBCA, pH, conductivity, spectrophotometry, endotoxin, Bioburden
- methods requiring specific development: WB, RP-, SE- & IEx-HPLC, HCP, rDNA, restriction mapping, ELISA, activity tests
The purified material (recombinant protein and plasmid) is characterized using the following assays:
| Tests | Methods for recombinant proteins | Methods for plasmids |
|---|---|---|
|
Physical state |
pH, conductivity and appearance | |
|
Identity |
SDS-PAGE |
Restriction mapping |
|
Western blotting |
DNA sequencing |
|
|
Iso-electrofocusing |
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|
Mass spectroscopy (ESI-Q-TOF, peptide mapping) |
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|
RP- & IEx-HPLC |
||
|
Content |
µBCA |
Spectrophotometry - A260 |
|
Spectrophotometry - A280 |
||
|
Purity |
SDS-PAGE (reducing and non-reducing conditions) |
Spectrophotometry - ratio A260/A280 |
|
RP & IEx-HPLC |
Topology by agarose gel electrophoresis |
|
|
SE-HPLC |
Topology by IEx-HPLC |
|
|
Impurity |
Residual host cell proteins by ELISA |
Residual host cell proteins by µBCA |
|
Residual host cell DNA by threshold |
Residual host cell DNA by q-PCR |
|
|
Residual host cell RNA by agarose gel electrophoresis or HPLC |
||
|
Safety |
Endotoxin content by LAL |
|
|
Bioburden |
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|
Potency |
Specific test (ELISA, specific activity…) |
Specific test |