Products from polycrystalline DNA constituents after X-irradiation and heavy-ion bombardment: Formation of the 5,6-dihydroadduct in thymidine 5 '-monophosphate and release of unaltered bases in nucleotides

Citation
Ak. Hoffmann et J. Huttermann, Products from polycrystalline DNA constituents after X-irradiation and heavy-ion bombardment: Formation of the 5,6-dihydroadduct in thymidine 5 '-monophosphate and release of unaltered bases in nucleotides, INT J RAD B, 76(9), 2000, pp. 1167-1178
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Experimental Biology
Journal title
INTERNATIONAL JOURNAL OF RADIATION BIOLOGY
ISSN journal
0955-3002 → ACNP
Volume
76
Issue
9
Year of publication
2000
Pages
1167 - 1178
Database
ISI
SICI code
0955-3002(200009)76:9<1167:PFPDCA>2.0.ZU;2-C
Abstract
Purpose: The major products from polycrystalline purine and pyrimidine DNA nucleotides after low- and high-LET irradiation were investigated quantitat ively by HPLC and H-1-NMR spectroscopy. Materials and methods: Solid nucleotide samples were either X-irradiated as cylindrical pellets or heavy-ion bombarded (LET range of 100-12500 keV/mu m) as very thin tablets at 300K. Product analysis was performed by HPLC and H-1-NMR. Results: For TMP the 5,6-dihydroadduct as found to be formed as product of electron reaction. In addition, all four DNA nucleotides showed a radiation -induced base release, which is probably connected with the oxidative radia tion action. The formation of the products was linear with dose up to 300 k Gy for X-irradiation or 200 kGy for heavy-ion bombardment. The estimation o f the radiation chemical yields revealed G-values of about 10(-7) molJ(-1) and were typically smaller for irradiation with charged particles than thos e for X-rays. After heavy-ion bombardment the G-values first increased with increasing LET and decreased for very heavy ions. Conclusions: The yields for base release from both purine and pyrimidine nu cleotides are comparable in magnitude. The 5,6-dihydroadduct from TMP is a major radiation induced product with larger yields than found for base rele ase after X-irradiation and comparable yields after heavy-ion bombardment. The LET dependence of the G-values for base release in nucleotides is simil ar and resembles the double strand break formation in DNA. The observed sim ilarity in the LET dependence of the G-values might derive from an inhomoge neous distribution of energy deposition resulting in 'clustered damage'.