A Chemical Mechanistic Path Leads the Way to Cellular Argpyrimidine

Area of Science:

• Biochemistry
• Chemical Biology
• Proteomics

Background:

• Argpyrimidine (APY) is a methylglyoxal-derived advanced glycation end-product (AGE) linked to various diseases.
• The non-enzymatic formation of APY makes its cellular localization and protein targets difficult to identify.

Purpose of the Study:

• To elucidate the chemical mechanism of APY formation from methylglyoxal (MGO).
• To investigate the role of protein residues and phosphorylation in APY formation.
• To explore the relationship between APY modification and cellular phosphorylation events.

Main Methods:

• Utilized a peptide model system and mass spectrometry to analyze APY formation pathways.
• Investigated the influence of tyrosine and serine residues, including phosphorylated forms, on APY generation.
• Performed quantitative bottom-up proteomics on MGO-treated cells to identify APY-modified proteins.

Main Results:

• Identified a [M + 144] mass species, likely tetrahydropyrimidine (THP), as a direct APY precursor, ruling out prior mechanisms.
• Demonstrated that APY formation does not require oxidation and releases formate, not CO2.
• Showed that tyrosine residues can act as general bases, and phosphorylated tyrosine/serine residues can promote APY formation.
• Proteomic analysis revealed a correlation between APY-modified proteins and phosphorylation-related cellular processes.

Conclusions:

• Defined a novel chemical pathway for APY formation from MGO.
• Established a mechanistic link between protein phosphorylation and MGO-driven glycation, including APY formation.
• Suggested significant crosstalk between cellular phosphorylation and glycation pathways.