The amino acid isomerization is an important form of post-translational modification (PTM) that is benefiting from ongoing method development. The isomerization of aspartate is one of the most common and significant modifications in terms of impact on the properties of protein biopharmaceuticals. The aspartic acid (Asp) can isomerize readily to form isoaspartic acid (isoAsp). The isomerization of Asp to isoAsp occurs frequently in biotherapeutics.
Yaohai-BioPharma offers a testing service for amino acid isomerization, which allows you to detect and characterize isoAsp by LC-MS.
We have been involved in the Protein Structural Characterization of various large molecules, including Recombinant Subunit Vaccines, Nanobodies/ VHHs/ Single-domain antibodies (sdAbs), Antibody Fragments, Hormones/Peptides, Cytokines, Growth Factors (GF), Enzymes, Collagens, etc.
Regulatory Requirements for Amino Acid Isomerization
According to the ICH Q6B guidelines, isomerized forms may be detected and characterized by chromatographic, electrophoretic and/or other relevant analytical methods.
Analytical Methods
| Analysis |
Methods |
| Amino Acid Isomerization |
Liquid Chromatography-Mass Spectrometry (LC-MS) after enzymatic cleavage |
Analytical Procedures
e.g., aspartic isomerization
1. Enzymatic cleavage at aspartic acid residue using the endoproteinase AspN
2. LC-MS and data analysis to quantify isoAsp/Asp ratio
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