The application of multiple reaction monitoring to assess ApoA-I methionine oxidations in diabetes and cardiovascular disease

• Methionine (M148) of apolipoprotein A-I is critical for LCAT function on HDL.
• We developed a method to monitor modified M148 on HDL using multiple reaction monitoring (MRM).
• An increase in oxidized M148 relative to the native peptide was observed in HDL isolated from research participants with diabetes and evidence of past cardiovascular disease.
• Monitoring of M148 oxidations using MRM can serve as a potential biomarker for diabetes complications.

The oxidative modification of apolipoprotein A-I’s methionine148 (M148) is associated with defective HDL function in vitro. Multiple reaction monitoring (MRM) is a mass spectrometric technique that can be used to quantitate post-translational modifications. In this study, we developed an MRM assay to monitor the abundance ratio of the peptide containing oxidized M148 to the native peptide in ApoA-I. Measurement of the oxidized-to-unoxidized-M148 ratio was reproducible (CV < 5%). The extent of methionine M148 oxidation in the HDL of healthy controls, and type 2 diabetic participants with and without prior cardiovascular events (CVD) were then examined. The results suggest a significant increase in the relative ratio of the peptide containing oxidized M148 to the unmodified peptide in the HDL of participants with diabetes and CVD (p < 0.001), compared to participants without CVD. Monitoring the abundance ratio of the peptides containing oxidized and unoxidized M148 by MRM provides a means of examining the relationship between M148 oxidation and vascular complications in CVD.

M148 Oxidation Monitored By MRM: a potential biomarker for diabetes and cardiovascular disease.Figure optionsDownload as PowerPoint slide