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Fast, flexible platforms for peptide quantification are needed, particularly for a discovery setting. This type of methodology would be especially advantageous in the case of amyloid beta (a?) peptides.
Erin E. Chambers1, Mary E. Lame2, and Diane M. Diehl1, 1Waters Corporation and 2Pfizer, Neuroscience Research Unit
Fast, flexible platforms for peptide quantification are needed, particularly for a discovery setting. This type of methodology would be especially advantageous in the case of amyloid beta (aβ) peptides. The deposition/formation of insoluble aggregates, or plaques, of aβ peptides in the brain is considered to be a critical event in the progression of Alzheimer's disease (AD) and thus has the attention of many researchers. A previous Waters application note (720003682en) described in detail the development of a fast, flexible SPE-LC–MS–MS platform for the quantification of multiple aβ peptides from human or monkey CSF for use in a biomarker or preclinical discovery setting. In this work, the mass spectrometry platform has been updated from the Xevo TQ MS to the Xevo TQ-S mass spectrometry system. This change facilitated both a 4× reduction in required sample size and a 4–5× increase in assay sensitivity. This work focuses on methods for the 1–38, 1–40, and 1–42 aβ, Table I.
Table I: Sequence, MW, and pI Information for Amyloid Peptides
LC system: Waters ACQUITY UPLC System
Column: ACQUITY UPLC BEH C18 300 Å, 2.1 × 150 mm, 1.7 µm, Peptide Separation Technology
SPE: Oasis MCX µElution 96-well plate, 50 µL human or animal CSF
MS system: Waters Xevo TQ-S, ESI+
Figure 1: Representative ESI+ MS-MS spectrum for amyloid 1-42 with fragment sequence ions labeled.
Figure 2: Representative UPLCâMSâMS analysis of amyloid 1-38, 1-40, and 1-42 peptides extracted from artificial CSF + 5% rat plasma.
Table II: Comparison of Standard Curve and QC Range Using Xevo TQ and TQ-S MS
Table IV: Average Deviation Values for all Overspike QC Samples
Table III: Baseline Levels of Amyloid Î² Peptides in Two Sources of Pooled Human CSF
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