INVESTIGATION OF HNO-INDUCED MODIFICATIONS IN VARIOUS SYSTEMS

HNO;nitroxyl;azanone;thiol;cysteine;sulfinamide;N-nitrosotryptophan;phospholamban;reactivity;reduction;hydrolysis;sulfenic acid;disulfide;caffeine;Chemistry

Keceli, GizemToscano, John P. ;

Johns Hopkins University

关键词: HNO;    nitroxyl;    azanone;    thiol;    cysteine;    sulfinamide;    N-nitrosotryptophan;    phospholamban;    reactivity;    reduction;    hydrolysis;    sulfenic acid;    disulfide;    caffeine;    Chemistry;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/37990/KECELI-DISSERTATION-2014.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Nitroxyl (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 investigate sulfinamide reduction, we have applied 15N-edited 1H-NMR techniques to sulfinamide detection and used this method to explore sulfinamide hydrolysis.Since HNO-derived modifications may depend on local environment, we have also investigated the reactivity of HNO with cysteine derivatives and C-terminal cysteine-containing peptides.Apart from the lack of sulfinamide formation, these studies have revealed the presence of new products, a sulfohydroxamic acid derivative [RS(O)2NHOH] and a thiosulfonate [RS(O)2SR], presumably produced under our experimental conditions via the intermediacy of a cyclic structure that is hydrolyzed to give a sulfenic acid (RSOH).Apart from its role in thiol oxidation, HNO has been reported to have nitrosative properties, for example with tryptophan resulting in N-nitrosotryptophan formation.We have examined the reactivity of HNO with tryptophan and small peptides containing either tryptophan or both a tryptophan and a cysteine residue.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 proteins, phospholamban (PLN) and sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2a) were investigated.