Mass spectrometric analysis of asparagine deamidation and aspartate isomerization in polypeptides

• Published in: Electrophoresis Vol. 31; no. 11; pp. 1764 - 1772
• Main Authors: Yang, Hongqian, Zubarev, Roman A
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley-VCH Verlag 01.06.2010; WILEY-VCH Verlag; WILEY‐VCH Verlag
• Subjects: Aging; Amides - chemistry; Amides - metabolism; Animals; Asparagine - chemistry; Asparagine - metabolism; Aspartates; Aspartic Acid - chemistry; Aspartic Acid - metabolism; Cell regulation; Electrophoresis; Electrophoresis, Gel, Two-Dimensional; Enzymes; Humans; Isoaspartate; Isomerism; Isomerization; Mass Spectrometry - methods; Medicin och hälsovetenskap; Mice; Physiology; Proteins; Proteomics - methods; Spectroscopy; Spontaneous
• ISSN: 0173-0835; 1522-2683; 1522-2683
• DOI: 10.1002/elps.201000027

One of the most frequent modifications in proteins and peptides is the deamidation of asparagine, a spontaneous non-enzymatic reaction leading to a mixture of L,D-succinimidyl, L,D-aspartyl, and L,D-isoaspartyl forms, with L-isoaspartyl dominating. Spontaneous isomerization of L-Asp yields the same products. In vivo, these unusual forms of aspartate are repaired by the protein L-isoaspartyl O-methyltransferase enzyme, with the balance between isomerization and repair affecting the organism physiology. Mass spectrometric analysis of this balance involves isomer separation, iso-Asp/Asp quantification, and iso-Asp site identification. This review highlights the issues associated with these steps and discusses the prospects of high-throughput iso-Asp analysis.