分析および生物分析技術ジャーナル

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Identification of X. laevis Vitellogenin Peptide Biomarkers for Quantification by Liquid Chromatography Tandem Mass Spectrometry

Leah G Luna and Katherine Coady

Mass spectrometry (MS) offers an exciting possibility as a highly specific method for measuring vitellogenin (VTG) concentrations in toxicity tests that are aimed at evaluating perturbations in the endocrine system. Typically MS approaches to protein quantification attempt to measure intact proteins or rely on enzymatic digestion procedures to reduce the size of the protein into smaller peptide fragments which can be utilized as biomarkers for quantification. With the latter approach, the MS technique allows both the direct measurement of the VTG intact peptide biomarker mass-to-charge ratio and the generation of peptide fragmentation data for further confirmation in complex matrices. In this study we utilize trypsin digestion and a C₁₈ Zip Tip clean-up method to generate predictably cleaved peptides to identify VTG biomarkers from small quantities of plasma collected from the African clawed frog (Xenopus laevis). From the 201,545 Da X. laevis VTG precursor protein, results indicate 2 peptides which would be excellent biomarker candidates for the quantitative measurements of VTG. This methodology may be particularly useful in the context of the Larval Amphibian Growth and Development Assay, a Tier 2 test which is currently under development as a part of the United States Environmental Protection Agency’s Endocrine Disruptor Screening Program.