Chemical approaches to detect and analyze protein sulfenic acids

Abstract

Orchestration of many processes relying on intracellular signal transduction is recognized to require the generation of hydrogen peroxide as a second messenger, yet relatively few molecular details of how this oxidant acts to regulate protein function are currently understood. This review describes emerging chemical tools and approaches that can be applied to study protein oxidation in biological systems, with a particular emphasis on a key player in protein redox regulation, cysteine sulfenic acid. While sulfenic acids (within purified proteins or simple mixtures) are detectable by physical approaches like X-ray crystallography, nuclear magnetic resonance and mass spectrometry, the propensity of these moieties to undergo further modification in complex biological systems has necessitated the development of chemical probes, reporter groups and analytical approaches to allow for their selective detection and quantification. Provided is an overview of techniques that are currently available for the study of sulfenic acids, and some of the biologically meaningful data that have been collected using such approaches.

Differential cytotoxic and radiosensitizing effects of silver nanoparticles on triple-negative breast cancer and non-triple-negative breast cells

“…Assessment of protein-SOH provides quantitative information on potential oxidative damage at a critical point from which altered cell signaling, regulatory and toxic outcomes may arise. 44 We note a dose-dependent increase in protein-SOH in MCF-7 following exposure to AgNPs, but we observe far more protein-SOH in triplenegative MDA-MB-231 following exposure to AgNPs at 10 μg/mL. However, lower levels of protein-SOH are detected in MDA-MB-231 cells treated with AgNPs at 25 μg/mL than the following treatment at10 μg/mL.…”

“…44 Quantification of protein-SOH in cells provides a sensitive means to measure oxidative damage. To assess the potential for AgNP exposure to generate protein-SOH, we incubated MDA-MB-231, MCF-7, or MCF-10A cells with AgNPs at 10 or 25 μg/mL then probed for protein-SOH using a biotin-1,3-cyclopentanedione probe as previously described.…”

Endogenous, regulatory cysteine sulfenylation of ERK kinases in response to proliferative signals

“…A strongly positive aspect of using DCP-Bio1 to detect protein oxidation is that it labels cysteines undergoing direct and active oxidation. However, it should be noted that, because DCP-Bio1 detects only the likely transient sulfenic acid (or potentially sulfenylamide [16, 17]) intermediate, it does not report on the total pool of oxidized protein.…”

“…1A). Using these dimedone-based probes to capture proteins undergoing active oxidation in cells responding to external signals can reveal the identity of the proteins oxidized in situ , and in favorable cases the specific cysteine residue undergoing oxidation [16, 26]. …”

The redox switch that regulates molecular chaperones

“…The redox potential is also dictated by the amino acids that are flanked by the reactive thiols. Oxidation of thiolate anions first generates a cysteine sulphenic acid [ Figure 1A (i)], which can be identified using chemical-specific probes such as dimedone or with mass spectrometry (10). Cysteine sulphenic acids are considered highly unstable transient intermediates with a propensity to form more stable associations with other accessible cysteine residues.…”