Key result
HNO modifies cysteine residues to sulfinamides, with reactivity influenced by the local environment such as the C-terminal carboxylate.
HNO modifies cysteine residues to sulfinamides, which undergo specific reduction and hydrolysis reactions that may underlie its mechanism of action as a potential heart failure therapeutic targeting phospholamban.
May support HNO as heart failure therapy via phospholamban; hypothesis-generating from animal data, clinical translation unproven.
HNO, a potential heart failure therapeutic, is known to post-translationally modify cysteine residues. Among reactive nitrogen oxide species, the modification of cysteine residues to sulfinamides [RS(O)NH2] is unique to HNO. Because this modification can alter protein structure and function, we have examined the reactivity of sulfinamides in several systems, including small organic molecules, peptides, and a protein. At physiological pH and temperature, relevant reactions of sulfinamides involve reduction to free thiols in the presence of excess thiol and hydrolysis to form sulfinic acids [RS(O)OH]. In addition to utilizing ESI-MS and other spectroscopic methods to study sulfinamide reduction, we have applied 15N-edited 1H-NMR techniques to sulfinamide detection and used this method to explore sulfinamide hydrolysis. We have also investigated the effect of local environment on the reactivity of HNO with C-terminal cysteines. Our findings indicate that the nature of HNO-derived modifications of C-terminal cysteines is influenced by the C-terminal carboxylate. HNO has been shown to enhance cardiac sarcoplasmic reticulum Ca2+ cycling independent of the β-adrenergic pathway. In a collaborative project, the effects of HNO on the cardiac protein, phospholamban (PLN) are investigated using 15N-edited NMR methods and biochemistry protocols. This research was supported by the National Science Foundation (CHE-1213438) and Cardioxyl Pharmaceuticals.
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Keceli et al. (2015) studied Heart failure. HNO was evaluated on Reactivity of sulfinamides and effects of HNO on phospholamban. HNO modifies cysteine residues to sulfinamides, with reactivity influenced by the local environment such as the C-terminal carboxylate.
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