Fundamental Sessions
Day 1, June 10（Wed.） 13:50-14:08 Room D (5F 511+512)
- 1D-O1-1350（2P-02）
Development of a Rapid Asp Isomerization Rate Evaluation Method Based on Fragment Ion Generation Behavior in MS/MS
(1Kyoto Univ., 2Teikyo Univ., 3Kyoto Univ.)
oMone Yurugi1, Norihiko Fujii2, Takumi Takata3
Aspartic acid (Asp) residues can spontaneously form β-linked isoaspartate (β-Asp) in proteins, disrupting the polypeptide backbone and potentially altering protein structure and function. This modification has been observed in age-related diseases such as Alzheimer’s disease and cataracts, representing a form of molecular aging of protein. The reaction proceeds via a cyclic succinimide intermediate and can also arise from asparagine deamidation. Because Asp and β-Asp share identical molecular masses, their differentiation and quantification remain technically challenging, and systematic methods to evaluate factors affecting Asp isomerization have not been fully established.
To address this issue, we developed a rapid and simple mass spectrometry-based method to evaluate β-linkage formation. While conventional MS/MS approaches such as CID or ECD/ETD have been used for β-Asp identification, they require complex optimization or involve incompletely understood fragmentation behavior. By focusing on β-Asp-specific fragmentation in CID, we demonstrate that the relative β-Asp content in synthetic peptides can be determined using the intensity ratio of the yl–n−73 fragment ion to the corresponding yl–n ion. This method is applicable to trypsin-digested proteins, does not require chromatographic separation, and enables rapid, scalable comparative analysis across multiple samples.