Mass spectrometry-based quantitative proteomics: Development of allergenic food protein detection method & Evaluation of Tau phosphorylation sites as biomarkers for the diagnosis of Alzheimer’s disease

Abstract

There are two modes of quantitative analysis using high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Multiple reaction monitoring (MRM) on a triple quadrupole is widely used for quantification with high specificity and reproducibility. Recently, Parallel reaction monitoring (PRM) on a quadrupole orbitrap is developed with high resolution, mass accuracy and sensitivity, and has been used for quantitative analysis. In this study, MRM and PRM were used to identify and quantify the marker peptides of allergenic food proteins in part 1, and PRM were used to quantify phosphorylated tau (p-tau) peptides in plasma in part 2. In addition, stable isotope labeled (SIL) peptides were used for absolute quantification in part 1 and 2. In part 1, development of allergenic food protein detection method was performed in walnuts, wheat, beef, pork, and mackerel foods. A food allergy is an Immunoglobulin E (IgE) mediated reaction to certain food ingredients. It is important to accurately detect and label specific foods because no therapeutic drug has been developed. Therefore, we analyzed various processed foods containing each food ingredient, developed quantification method and validated marker peptides which are not affected by processing. In part 2, phosphorylated tau (p-tau) peptides in plasma were evaluated as biomarkers for diagnosis of Alzheimer's disease (AD) stage. AD is the most common major dementia of neurodegenerative disorder and is classified into preclinical, mild cognitive impairment, and dementia according to disease progression. Because AD biomarker that precisely distinguishes the AD stage has not yet been developed, we performed quantitative analysis of p-tau peptides in plasma using PRM and evaluated as biomarkers against different stage of AD.