Targeted quantitative mass spectrometric immunoassay for human protein variants

Area of Science:

• Biochemistry
• Proteomics
• Analytical Chemistry

Background:

• Human proteome complexity arises from post-translational modifications and genetic variations, creating diverse protein variants.
• Standard immunoassays cannot distinguish protein variants, limiting their utility as biomarkers.
• Mass spectrometry coupled with immunoaffinity separation enables simultaneous detection and quantification of protein variants.

Purpose of the Study:

• To develop a mass spectrometric immunoassay for targeted quantitative proteomics of protein modifications.
• To establish an assay for precise quantification of Cystatin C variants as potential biomarkers.

Main Methods:

• Development of a mass spectrometric immunoassay incorporating an internal reference standard for normalization.
• Benchmarking the new assay against existing Cystatin C enzyme-linked immunosorbent assays (ELISA).
• Application of the assay to quantify individual Cystatin C variants in a sample cohort.

Main Results:

• The assay demonstrated established precision, linearity, and recovery characteristics.
• The mass spectrometric immunoassay successfully quantified individual Cystatin C variants.
• The method provides a significant advancement over traditional immunoassays for variant analysis.

Conclusions:

• Mass spectrometric immunoassays are valuable for quantifying specific protein modifications and variants.
• These assays can support biomarker discovery efforts for disease onset, progression, and therapy response.
• The methodology contributes to a deeper understanding of human protein diversity.