Naslov
One-Electron Reduction of Selenomethionine Oxide

Autori
Assmann, Annika ; Bonifačić, Marija ; Briviba, Karlis ; Sies, Helmut ; Asmus, Klaus-Dieter

Izvornik
Free Radical Research (1071-5762) 32 (2000), 4; 371-376

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Radovi u časopisima, članak, znanstveni

Ključne riječi
methionine oxide; oxidation; pulse radiolysis; radicals; selenmethionine

Sažetak
The present work demonstrates high reducibility of selenomethionine oxide (MetSeO) in comparison to methionine sulfoxide, its sulfur analogue, with respect to one-electron transfer reactions. As shown by pulse radiolysis techniques MetSeO reacts very efficiently with one-electron reductants, such as a e^aq^ (k = 1.2x10^10^ M^-1^s^-1^), CO"2"^.^ (k = 5.9x10^8^ M^-1^s^-1^), and (CH"2")"2"C^?^OH (k = 3.5x10^7^ M^-1^s^-1^) forming an intermediate selenium-nitrogen coupled zwitterionic radical with the positive charge at an intermolecularly formed Se..N 2sigma/1sigma^*^ three-electron bond. The latter is characterized by an optical absorption with lambda^max^ 375 nm, and a half life of about 70 mikros. The same transient can be generated upon ^.^OH or ^.^N"3" radical-induced oxidation of selenomethionine (MetSe). This radical thus constituents the redox intermediate between the two oxidation states, MetSeO and MetSe. Evidence has been obtained for a reaction of this transient with glutathione in which the Se..N species seems to be reduced to MetSe while the glutathione is oxidized to the GS^.^ free radical. The time-resolved optical data further indicate possible sulfur-selenium interaction. The Se..N transient may play a key role in reduction of selenomethionine oxide by antioxidants, i.e. glutathione.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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