Nalazite se na CroRIS probnoj okolini. Ovdje evidentirani podaci neće biti pohranjeni u Informacijskom sustavu znanosti RH. Ako je ovo greška, CroRIS produkcijskoj okolini moguće je pristupi putem poveznice www.croris.hr
izvor podataka: crosbi !

EPR evidence for Sigma -Radicals in Irradiated Thiothymine in a Single Crystal (CROSBI ID 477317)

Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija

Bešić, Erim ; Sanković, Krešimir ; Herak, Janko N. EPR evidence for Sigma -Radicals in Irradiated Thiothymine in a Single Crystal // XIX International Conference on Magnetic Resonance in Biological Systems - Book of Abstracts / Banci, Lucia ; Bertini, Ivano (ur.). Firenza : München, 2000. str. 313 - 313-x

Podaci o odgovornosti

Bešić, Erim ; Sanković, Krešimir ; Herak, Janko N.

engleski

EPR evidence for Sigma -Radicals in Irradiated Thiothymine in a Single Crystal

Thionucleobases have been used as instrinsic photolabels to probe the structure and organization of RNA molecules in solution and to identify the contacts between nucleic acids and proteins in nucleoprotein complexes (1). The thioanalogs of the nucleic-acid bases absorb light at long wavelengths and can be selectively photoactivated into the electronic triplet state, leading to their high affinity to crosslink to other nucleic-acid bases and amino-acid residues in contact. Here we show that thionucleobases behave different from natural nucleic-acid bases also when irradiated by radiation of much higher energy (gamma-rays). In irradiated regular (non-thiolated) nucleic-acid bases in the crystals only pi-type radicals are found. In the crystalline thionucleobases the radicals of the sigma-type are observed. The sigma-type radicals have been studied in detail in the irradiated single crystal of thiothymine. The maximum value of the g tensor coincides with the direction of the C-S bond, indicating the dominant contribution of the spin density in one of the sulfur p orbitals perpendicular to that bond. The radical is formed by ultimate release of the H-1 proton, leaving a significant spin density (about 10%) in the N(1) non-bonding sp2 atomic orbital, as concluded from the nitrogen N-1 hyperfine splitting tensor. The observation is consistent with the idea that the high-energy radiation induces ionization by knocking out one of the electrons from the sulfur non-bonding orbital. The resulting cation is neutralized by subsequent deprotonation at N-1. References: 1. Favre A., Saintome C., Fourrey J.L., Laugaa P., J.Photochem. Photobiol. B 42, 109-124 (1998). Acknowledgement: This work has been supported by the Croatian Ministry of Science and Technology.

EPR; sigma-radicals; thiothymine

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

Podaci o prilogu

313 - 313-x.

2000.

objavljeno

Podaci o matičnoj publikaciji

XIX International Conference on Magnetic Resonance in Biological Systems - Book of Abstracts

Banci, Lucia ; Bertini, Ivano

Firenza : München:

Podaci o skupu

XIX International Conference on Magnetic Resonance in Biological Systems - Magnetic Resonance for the Life Sciencesin the Twenty-First Century

poster

20.08.2000-25.08.2000

Firenca, Italija

Povezanost rada

Temeljne medicinske znanosti