Authentication of a protein as the protein of interest sounds like a trivial matter. However, when working with a protein that has been isolated from a complex mixture of other proteins it is important to verify that the correct protein has been isolated. This is easily accomplished by various peptide mapping procedures with or without mass spectrometry. One of the easiest methods is known as peptide mass fingerprinting where a purified protein is proteolyzed with an enzyme such as trypsin and the resulting peptides are analyzed by mass spectrometry. Confirmation of identity is demonstrated by showing that the expected peptide masses are found in the digest. An alternative method is western blotting where a specific antibody is used to demonstrate immunoreactivity with a protein separated by SDS-PAGE. Several techniques are available to conduct this testing as shown below. Some techniques are dependent on the molecular weight of the protein ( < or > 5000).
- Mass Spectrometry
- ESI Triple Quad
- MALDI-TOF
- LC/MS
- LC/MS/MS
- Peptide mapping
- Western blotting
The techniques that will be applied to Comparability Testing are the same techniques that are described above. This service will be offered to customers as a means of assessing whether process changes have had an effect on the properties of a protein drug substance. Numerous tests are offered and the customer can decide to choose those tests that are most relevant for their needs; after running the battery of tests and presenting the data, the customer can then decide which tests are to be run for every process change. The full list of comparability testing consists of:
- Peptide mapping (reduced and non-reduced)
- SDS-PAGE
- IEF
- RP-HPLC
- MALDI-TOF mass spec analysis on intact protein
- Endotoxin determination
- Size exclusion chromatography
- Dynamic light scattering
- N-terminal sequence analysis
- Differential scanning Calorimetry
- Thermogravimetric Analysis
- FT-IR spectroscopy
- Raman spectroscopy
- XRPD
Other tests may be available, please inquire: info@ssci-inc.com