Analytical quality
Oxidation and deamidation in stability studies
Oxidation and deamidation: Was the modification already present or introduced during preparation?
Source editorial review:
Before interpreting the result
Was the modification already present or introduced during preparation?
- Identify the modification and site without treating oxidation and deamidation as equivalent.
- Separate storage, deliberate stress and analytical preparation.
- Keep the chemical measurement separate from any subsequent functional assay.
Oxidation and deamidation
Oxidation and deamidation are classes of chemical transformation that can alter mass, charge or analytical behavior depending on the particular change. A different signal alone identifies neither the process nor its location. Stability studies should link loss of initial material with appearance and characterization of relevant species within the method's capabilities.
A reading case: what to check
If an aged sample develops another peak, treat 'oxidation' as a hypothesis until appropriate evidence exists. Compare mass, fragmentation or other relevant measurements and examine procedural interference. Approximate agreement does not necessarily locate the modified residue. The review record should separate observed change, proposed assignment and degree of confirmation.
What to preserve in the record
Detecting a modified species does not establish when it appeared or which function changed. The conclusion needs suitable temporal and analytical controls before attributing the change to vial storage.
Questions and answers
Was the modification already present or introduced during preparation?
Oxidation and deamidation are classes of chemical transformation that can alter mass, charge or analytical behavior depending on the particular change. A different signal alone identifies neither the process nor its location. Stability studies should link loss of initial material with appearance and characterization of relevant species within the method's capabilities.
What should the review record preserve?
Detecting a modified species does not establish when it appeared or which function changed. The conclusion needs suitable temporal and analytical controls before attributing the change to vial storage.
Sources
- Methionine oxidation in human IgG2 Fc decreases binding affinities to protein A and FcRn
- Comparison of methionine oxidation in thermal stability and chemically stressed samples of a fully human monoclonal antibody
- Determination of deamidation artifacts introduced by sample preparation using 18O-labeling and tandem mass spectrometry analysis