TY - JOUR
T1 - Ultraviolet-induced changes in DNA
T2 - Possible confusion of repair and degradative enzymes
AU - Slor, Hanoch
AU - Lev, Tama
N1 - Funding Information:
We wish to thank Dr J. E. Cleaver for his critical review and helpful discussions during the preparation of this manuscript and Miss Sima Portnoi for technical assistance. This research was supported in part by the Israel Cancer Association. Some of the experiments were done at the Laboratory of Radiobiology, University of California, San Francisco, Calif. under the auspices of the U.S. Atomic Energy Commission.
PY - 1973/7/27
Y1 - 1973/7/27
N2 - It has recently been reported (Burt, D. H. and Brent, T. P. (1971) Biochem. Biophys. Res. Commun. 43, 1382-1387) that a deoxyribonuclease specific for ultraviolet-irradiated DNA is found in crude extracts of HeLa cells. We find a similar deoxyribonuclease activity in both normal and xeroderma pigmentosum cells, which indicates that the activity is not correlated with the defective excision repair in xeroderma pigmentosum cells. This raises the possibility that the deoxyribonuclease activity is not really specific for ultraviolet-irradiated DNA. Our results show that irradiation of DNA with extremely high doses produces extensive breaks and partial denaturation of the DNA. Use of DNA irradiated with high ultraviolet doses as a substrate for deoxyribonucleases detected an enzyme which degraded the single-stranded regions of DNA rather than attacking the ultraviolet photoproducts. The enzyme was partially purified by electrophoresis and was in fact found to be an exonuclease specific for single-stranded DNA.
AB - It has recently been reported (Burt, D. H. and Brent, T. P. (1971) Biochem. Biophys. Res. Commun. 43, 1382-1387) that a deoxyribonuclease specific for ultraviolet-irradiated DNA is found in crude extracts of HeLa cells. We find a similar deoxyribonuclease activity in both normal and xeroderma pigmentosum cells, which indicates that the activity is not correlated with the defective excision repair in xeroderma pigmentosum cells. This raises the possibility that the deoxyribonuclease activity is not really specific for ultraviolet-irradiated DNA. Our results show that irradiation of DNA with extremely high doses produces extensive breaks and partial denaturation of the DNA. Use of DNA irradiated with high ultraviolet doses as a substrate for deoxyribonucleases detected an enzyme which degraded the single-stranded regions of DNA rather than attacking the ultraviolet photoproducts. The enzyme was partially purified by electrophoresis and was in fact found to be an exonuclease specific for single-stranded DNA.
UR - https://www.scopus.com/pages/publications/0015882254
U2 - 10.1016/0005-2787(73)90067-1
DO - 10.1016/0005-2787(73)90067-1
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C2 - 4795242
AN - SCOPUS:0015882254
SN - 0005-2787
VL - 312
SP - 637
EP - 644
JO - BBA Section Nucleic Acids And Protein Synthesis
JF - BBA Section Nucleic Acids And Protein Synthesis
IS - 4
ER -