Double-base lesions are produced in DNA by free radicals.
Evidence has been accumulating at the oligomer level that free radical-initiated DNA damage includes lesions in which two adjacent bases are both modified. Prominent examples are lesions in which a pyrimidine base is degraded to a formamido remnant and an adjacent guanine base is oxidized. An assay has been devised to detect double-base lesions based on the fact that the phosphoester bond 3' to a nuclesoside bearing the formamido lesion is resistant to hydrolysis by nuclease P1. The residual modified dinucleoside monophosphates obtained from a nuclease P1 (plus acid phosphatase) digest of DNA can be (32)P-postlabeled using T4 polynucleotide kinase. Using this assay the formamido single lesion and the formamido-8-oxoguanine double lesion were detected in calf thymus DNA after X-irradiation in oxygenated aqueous solution. The lesions were measured in the forms d(P(F)pG) and d(P(F)pG(H)), where P(F) stands for a pyrimidine nucleoside having the base degraded to a formamido remnant and G(H) stands for 8-oxo-deoxyguanosine. The yields in calf thymus DNA irradiated 60 Gy were 8.6 and 3.2 pmol/microgram DNA, respectively.
Maccubbin
A E
AE
Department of Molecular Biophysics, Roswell Park Cancer Institute, Buffalo, New York, 14263, USA.
Iijima
H
H
Ersing
N
N
Dawidzik
J B
JB
Patrzyc
H B
HB
Wallace
J C
JC
Budzinski
E E
EE
Freund
H G
HG
Box
H C
HC
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000737:chemistry; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D005559:Formamides / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D006147:Guanine / Q000031:analogs & derivatives / Q000737:chemistry; D011741:Pyrimidine Nucleosides / Q000737:chemistry; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013941:Thymine / Q000031:analogs & derivatives / Q000737:chemistry; D013950:Thymus Gland; D014965:X-Rays
D005559:Formamides; D005609:Free Radicals; D011741:Pyrimidine Nucleosides; C029389:thymine glycol; C040829:N(6)-methyldeoxyadenosine 5'-triphosphate; C024829:8-hydroxyguanine; D006147:Guanine; D000255:Adenosine Triphosphate; D004247:DNA; D015719:Single-Strand Specific DNA and RNA Endonucleases; D013941:Thymine