18O2-labeling in quantitative proteomic strategies: a status report

Area of Science:

• Biochemistry
• Proteomics
• Analytical Chemistry

Background:

• Accurate protein quantification is crucial in biological research and clinical diagnostics.
• Existing labeling methods may have limitations in universality and sensitivity.
• Post-translational modifications can complicate protein analysis.

Purpose of the Study:

• To review the enzyme-catalyzed oxygen-18 (¹⁸O) labeling technique for peptide labeling.
• To discuss the strengths and limitations of this universal labeling strategy.
• To advocate for optimized methodologies for protein abundance determination.

Main Methods:

• Enzyme-catalyzed ¹⁸O₂ labeling of peptides.
• Separation of proteolysis and labeling steps.
• Analysis of labeled peptides using mass spectrometry (implied).

Main Results:

• Enzyme-catalyzed ¹⁸O₂-labeling enables uniform labeling of all peptides, including those from post-translationally modified proteins.
• The method demonstrates high sensitivity, suitable for clinical sample analysis.
• Separating proteolysis from labeling enhances the technique's applicability.

Conclusions:

• Enzyme-catalyzed ¹⁸O₂-labeling is a versatile and sensitive approach for comprehensive peptide labeling.
• Optimizing the workflow, particularly by separating proteolysis from labeling, is recommended.
• Advancements in software will further promote the use of this technique for quantifying protein abundance changes.