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Research at the interface between chemistry and the -omic sciences and systems biology.
Paper
Mol. BioSyst., 2008, 4, 521 - 531, DOI: 10.1039/b719986d
A chemical approach for detecting sulfenic acid-modified proteins in living cells
Khalilah G. Reddie, Young Ho Seo, Wilson B. Muse III, Stephen E. Leonard and Kate S. Carroll
Oxidation of the thiol functional group in cysteine (Cys–SH) to sulfenic (Cys–SOH), sulfinic (Cys–SO2H) and sulfonic acids (Cys–SO3H) is emerging as an important post-translational modification that can activate or deactivate the function of many proteins. Changes in thiol oxidation state have been implicated in a wide variety of cellular processes and correlate with disease states but are difficult to monitor in a physiological setting because of a lack of experimental tools. Here, we describe a method that enables live cell labeling of sulfenic acid-modified proteins. For this approach, we have synthesized the probe DAz-1, which is chemically selective for sulfenic acids and cell permeable. In addition, DAz-1 contains an azide chemical handle that can be selectively detected with phosphine reagents via the Staudinger ligation for identification, enrichment and visualization of modified proteins. Through a combination of biochemical, mass spectrometry and immunoblot approaches we characterize the reactivity of DAz-1 and highlight its utility for detecting protein sulfenic acids directly in mammalian cells. This novel method to isolate and identify sulfenic acid-modified proteins should be of widespread utility for elucidating signaling pathways and regulatory mechanisms that involve oxidation of cysteine residues.
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