Authors:	Schildknecht, Stefan Kriegsheim, Alex von Vujacic-Mirski, Ksenija Di Lisa, Fabio Ullrich, Volker Daiber, Andreas
Title:	Recovery of reduced thiol groups by superoxide-mediated denitrosation of nitrosothiols
Online publication date:	25-Jan-2023
Year of first publication:	2022
Language:	english
Abstract:	Nitrosation of critical thiols has been elaborated as reversible posttranslational modification with regulatory function in multiple disorders. Reversibility of S-nitrosation is generally associated with enzyme-mediated one-electron reductions, catalyzed by the thioredoxin system, or by nitrosoglutathione reductase. In the present study, we confirm previous evidence for a non-enzymatic de-nitrosation of nitrosoglutathione (GSNO) by superoxide. The interaction leads to the release of nitric oxide that subsequently interacts with a second molecule of superoxide (O2•−) to form peroxynitrite. Despite the formation of peroxynitrite, approximately 40–70% of GSNO yielded reduced glutathione (GSH), depending on the applied analytical assay. The concept of O2•− dependent denitrosation was then applied to S-nitrosated enzymes. S-nitrosation of isocitrate dehydrogenase (ICDH; NADP+-dependent) was accompanied by an inhibition of the enzyme and could be reversed by dithiothreitol. Treatment of nitrosated ICDH with O2•− indicated ca. 50% recovery of enzyme activity. Remaining inhibition was largely consequence of oxidative modifications evoked either by O2•− or by peroxynitrite. Recovery of activity in S-nitrosated enzymes by O2•− appears relevant only for selected examples. In contrast, recovery of reduced glutathione from the interaction of GSNO with O2•− could represent a mechanism to regain reducing equivalents in situations of excess O2•− formation, e.g. in the reperfusion phase after ischemia.
DDC:	610 Medizin 610 Medical sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 04 Medizin
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-8634
Version:	Published version
Publication type:	Zeitschriftenaufsatz
Document type specification:	Scientific article
License:	CC BY-NC-ND
Information on rights of use:	https://creativecommons.org/licenses/by-nc-nd/4.0/
Journal:	Redox Biology 56
Pages or article number:	102439
Publisher:	Elsevier
Publisher place:	Amsterdam
Issue date:	2022
ISSN:	2213-2317
Publisher DOI:	10.1016/j.redox.2022.102439
Appears in collections:	DFG-491381577-G