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Titolo:
CHROMATIN STRUCTURE AND RADIATION-INDUCED DNA STRAND BREAKS IN HUMAN-CELLS - SOLUBLE SCAVENGERS AND DNA-BOUND PROTEINS OFFER A BETTER PROTECTION AGAINST SINGLE-STRAND THAN DOUBLE-STRAND BREAKS
Autore:
NYGREN J; LJUNGMAN M; AHNSTROM G;
Indirizzi:
UNIV STOCKHOLM,DEPT RADIOBIOL S-10691 STOCKHOLM SWEDEN UNIV MICHIGAN,DEPT RADIAT ONCOL ANN ARBOR MI 48109
Titolo Testata:
International journal of radiation biology
fascicolo: 1, volume: 68, anno: 1995,
pagine: 11 - 18
SICI:
0955-3002(1995)68:1<11:CSARDS>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
NEUTRAL FILTER ELUTION; IONIZING-RADIATION; GEL-ELECTROPHORESIS; MAMMALIAN-CELLS; DOSE-RESPONSE; DAMAGE; NUCLEAR; THYMINE; THIOLS; REPAIR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
38
Recensione:
Indirizzi per estratti:
Citazione:
J. Nygren et al., "CHROMATIN STRUCTURE AND RADIATION-INDUCED DNA STRAND BREAKS IN HUMAN-CELLS - SOLUBLE SCAVENGERS AND DNA-BOUND PROTEINS OFFER A BETTER PROTECTION AGAINST SINGLE-STRAND THAN DOUBLE-STRAND BREAKS", International journal of radiation biology, 68(1), 1995, pp. 11-18

Abstract

In the present investigation we have studied the formation of DNA double-strand breaks (dsbs) in different chromatin substrates and made a comparison with our previous results on radiation-induced single-strand breaks (ssbs). Removal of soluble scavengers increased the number ofssbs by a factor of 2, but increased dsbs only 1 . 2 times. Decondensation of the chromatin increased ssbs and dsbs to the same extent, by a factor of 3-4. Removal of DNA-bound proteins gave an additional increase in ssbs and dsbs by a factor of 14 and 5 respectively. The increase in both ssbs and dsbs was caused by OH radicals. The differential effect on ssbs and dsbs can be explained by assuming that dsbs are formed mainly by multiple hits from clusters of ionizations close to the DNA. When the DNA-bound proteins are removed, more distant radicals canreach the DNA, which favours ssb formation. Under those conditions dsbs also induced by single OH radicals become important. DNA-bound proteins protect DNA only to a limited extent by acting as scavengers of OH radicals. The largest part of the protection depends on the fact that DNA in the chromatin is made up of large, compact aggregates, where the distance between separate aggregates exceeds the effective range of the OH radicals and the amount of water inside the aggregates is toosmall to give a maximal contribution of OH radicals compared with when DNA is more evenly distributed in a given volume.

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Documento generato il 27/11/20 alle ore 12:38:24