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 language | English |
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Title of host publication | Taurine 10 |
Editors | Dong-Hee Lee, Stephen W. Schaffer, Eunkyue Park, Ha Won Kim |
Place of Publication | Dordrecht |
Publisher | Springer |
Pages | 551-561 |
Number of pages | 11 |
Volume | 975 |
ISBN (Electronic) | 9789402410792 |
ISBN (Print) | 9789402410778 |
DOIs | |
Publication status | Published - 2017 |
Event | 20th International Taurine Meeting: “Taurine and Brain Health” - Plaza Hotel, Seoul, Korea, Republic of Duration: 23 May 2016 → 27 May 2016 http://taurine2016.org/register/2016_met/main.html |
Publication series
Name | Advances in Experimental Medicine and Biology |
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Publisher | Springer |
Volume | 975 |
ISSN (Print) | 0065-2598 |
ISSN (Electronic) | 2214-8019 |
Conference
Conference | 20th International Taurine Meeting |
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Abbreviated title | INTAM20 |
Country/Territory | Korea, Republic of |
City | Seoul |
Period | 23/05/16 → 27/05/16 |
Internet address |
Keywords
- Hypotaurine
- Sulfonyl radicals
- Sulfinates
- Taurine
- Superoxide dismutase
- Antioxidants