Relative quantitative analysis of human plasma <i>O</i>‑sulfotyrosine using HPLC‑MS/MS in linear negative ion mode

Abstract

Sulfation has been recognized as a key post‑translational modification in regulating various cellular processes. By contrast, the development of detection methods for protein sulfation is hindered due to the lack of available immune antibodies and lability of this modification. Recently, the serum level of <em>O</em>‑sulfotyrosine was reported to be associated with a decline in renal function, indicating a potential diagnostic value of the <em>O</em>‑sulfotyrosine concentration for certain diseases. The present study describes a sensitive and reproducible method for the relative quantitative analysis of human plasma <em>O</em>‑sulfotyrosine using high performance liquid chromatography (HPLC)‑tandem mass spectrometry (MS/MS) in a linear negative ion mode. The increase in plasma <em>O</em>‑sulfotyrosine levels in patients with chronic kidney disease was confirmed. This method is sensitive and reproducible with a low extraction effect, good intraday precision and inter‑day repeatability. A significantly increased plasma <em>O</em>‑sulfotyrosine concentration was confirmed in patients with chronic kidney disease compared to the healthy controls. Thus, determining the <em>O</em>‑sulfotyrosine concentration in plasma may be an easy method which can reflect the sulfation level <em>in vivo</em> under physical and pathological conditions.