This is by far the most extensive service offering and can be subdivided into several services as shown below. For each of these services, the preferred analytical techniques are included.
One of the most critical aspects of protein characterization is the purity assessment. Biological products are typically mixtures of several components including process-related impurities, product-related substances, and product-related impurities. The product-related contaminants will be discussed in a later section as "related substances." Process-related impurities include such contaminants as host cell proteins, host cell DNA, components from the cell culture (eg, antibiotics), and components from down stream processing steps (eg, column leachates).
Protein methods for purity:
- SDS-PAGE
- Isoelectric focusing
- RP-HPLC
Isoelectric Focusing
Endotoxin is a term that refers to a chemically ill-defined mixture of bacterial cell wall components that are primarily proteoglycan in nature. Extremely small amounts of endotoxin can elicit a pyrogenic response with fever and other symptoms. It obviously is of critical importance to insure that endotoxin has been reduced to non-detectible levels in protein products that are used therapeutically. Host cell contaminants are also a common phenomenon in large molecule development and SSCI offers identification and characterization of these contaminants as well.
- Limulus amebocyte lysate (LAL) endotoxin assay
- Methods for Host cell contaminants/processing agent contamination
- Quantification
- Amino acid analysis
- Colorimetric protein assays
- Aggregation studies
- Dynamic light scattering
- Size exclusion chromatography (SEC)
- Sequence analysis
- Edman sequencing
- Mass spec
- Amino acid analysis
- Hydrolysis
- Pre-column Derivitization and HPLC
- LC/MS/MS available
- Higher order structure
- Vibrational Spectroscopy
- NMR (solid and liquid phase)
- X-ray diffraction (single crystal)
- Protein folding
- NMR
- Functional assay
- Spectroscopy
- Determination of extinction coefficient
- Amino acid analysis
- UV spectroscopy
Determination of Oxidation, De-Amidation, Acetylation, Proteolysis, Phosphorylation, Disulfide Bonding and Free Sulfhydrol Groups.
- Peptide mapping
- Disulfide linkage determination
- Peptide mapping of reduced and non-reduced protein
- Spectrometry
All of the analytical techniques at SSCI can be used for the characterization of biopharmaceutical reference standards. The customer supplies the material in the amount required and specifies the analytical methods of choice.