Aspartate Isomerization Assessment

With the entry into clinical trials and the development of candidate drugs increasing, the testing for the safety and efficacy evaluation has become more important. Compared with other molecular drugs, monoclonal antibodies are more susceptible to various post-translational modifications (PTM) during production, transportation, and storage, which will affect the stability of the drug molecule and the structure and function of the protein. Therefore, higher quality requirements have been also proposed for quality control analysis of various PTMs in potential drugs. Creative Biolabs is concerned with the modification and enhancement of various drugs, especially for antibodies, and our aspartate isomerization assay has been generated to further modify the antibodies and reduce the side effects and adverse reactions of testing drugs.

Introduction of Aspartate Isomerization

Aspartate isomerization is a spontaneous non-enzymatic PTM method. After isomerization of aspartic acid, a methylene group is inserted into the protein backbone, that is, the aspartate side chain reduced a methylene group, thus causing a change in the structure of the protein and protein function. Many studies have revealed that aspartate isomerization can affect the effectiveness of candidate drugs. For example, aspartic acid isomerization in the complementarity-determining regions (CDRs) of antibodies can reduce the receptor binding efficiency and can affect final drug efficacy.

Schematic structure of aspartate isomerization via computer simulation. Fig.1 Schematic structure of aspartate isomerization via computer simulation. (Takahashi, 2015)

Our Technologies for Aspartate Isomerization

When deamidation occurs in asparagine (N), aspartic acid isomerization is accompanied, and the level of isomerization and the level of non-isomerization are basically in the ratio of 3:1, generally including the NG region. Asparagine in the region of PENNY (P is valine, E is glutamic acid, and Y is tyrosine) is susceptible to deamidation and isomerization of aspartic acid.

At the level of intact antibodies, aspartic acid isomerization assays can be performed using ion exchange and affinity chromatography, typically analysis of aspartate isomerization at the peptide level. When analyzed by reverse phase chromatography (RP), generally isomerized peptides are eluted preferentially over the unisomerized peptides.

At present, collision-induced activation dissociation (CID) and high energy fragmentation (HCD) have been broadly used for secondary fragmentation in Creative Biolabs. As a complementary fragmentation method, ETD can provide fragment ions that are complementary to CID/HCD and characteristic of ETD, especially when performing long-peptide PTM of peptides and intact protein level analysis, thereby accurately determining the amino acid sequence and Information on PTM sites.


Creative Biolabs focuses on the modification and improvement of a number of candidate drugs by aspartate isomerization, providing a reliable analytical method for accurate, rapid and fine analysis of your targets. If you want to know more details, please contact us or send us an inquiry.


  1. Takahashi, O.; et al. Acetic acid can catalyze succinimide formation from aspartic acid residues by a concerted bond reorganization mechanism: a computational study. International Journal of Molecular Sciences. 2015, 16(1): 1613-1626.

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