Carbonate Anion Radical Generated by the Peroxidase Activity of Copper-Zinc Superoxide Dismutase: Scavenging of Radical and Protection of Enzyme by Hypotaurine and Cysteine Sulfinic Acid

Alessia Baseggio Conrado, Simonetta Maina, Harry Moseley, Antonio Francioso, Luciana Mosca, Elisabetta Capuozzo, Mario Fontana

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)
169 Downloads (Pure)

Abstract

Copper-zinc superoxide dismutase (SOD) is considered one of the most important mammalian antioxidant defenses and plays a relevant role due to its main function in catalyzing the dismutation of superoxide anion to oxygen and hydrogen peroxide. However, interaction between SOD and H2O2 produced a strong copper-bound oxidant (Cu(II)(•)OH) that seems able to contrast the self-inactivation of the enzyme or oxidize other molecules through its peroxidase activity. The bicarbonate presence enhances the peroxidase activity and produces the carbonate anion radical (CO3(•-)). CO3(•-) is a freely diffusible reactive species capable of oxidizing several molecules that are unwieldy to access into the reactive site of the enzyme. Cu(II)(•)OH oxidizes bicarbonate to the CO3(•-), which spreads out of the binding site and oxidizes hypotaurine and cysteine sulfinic acid to the respective sulfonates through an efficient reaction. These findings suggest a defense role for sulfinates against the damage caused by CO3(•-) . The effect of hypotaurine and cysteine sulfinic acid on the CO3(•-)-mediated oxidation of the peroxidase probe ABTS to ABTS cation radical (ABTS(•+)) has been studied. Both sulfinates are able to inhibit the oxidation of ABTS mediated by CO3(•-). The effect of hypotaurine and cysteine sulfinic acid against SOD inactivation by H2O2 (~42% protection of enzyme activity) has also been investigated. Interestingly, hypotaurine and cysteine sulfinic acid partially avoid the H2O2-mediated SOD inactivation, suggesting that the two sulfinates may have access to the SOD reactive site and preserve it by reacting with the copper-bound oxidant. In this way hypotaurine and cysteine sulfinic acid not only intercept CO3(•-) which could move out from the reactive site and cause oxidative damage, but also prevents the inactivation of SOD.

Original languageEnglish
Title of host publicationTaurine 10
EditorsDong-Hee Lee, Stephen W. Schaffer, Eunkyue Park, Ha Won Kim
Place of PublicationDordrecht
PublisherSpringer
Pages551-561
Number of pages11
Volume975
ISBN (Electronic)9789402410792
ISBN (Print)9789402410778
DOIs
Publication statusPublished - 2017
Event20th International Taurine Meeting: “Taurine and Brain Health” - Plaza Hotel, Seoul, Korea, Republic of
Duration: 23 May 201627 May 2016
http://taurine2016.org/register/2016_met/main.html

Publication series

NameAdvances in Experimental Medicine and Biology
PublisherSpringer
Volume975
ISSN (Print)0065-2598
ISSN (Electronic)2214-8019

Conference

Conference20th International Taurine Meeting
Abbreviated titleINTAM20
CountryKorea, Republic of
CitySeoul
Period23/05/1627/05/16
Internet address

Keywords

  • Hypotaurine
  • Sulfonyl radicals
  • Sulfinates
  • Taurine
  • Superoxide dismutase
  • Antioxidants

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