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Endonucleolytic incision of UVB-irradiated DNA

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:6122150
Ultraviolet irradiation of DNA produces a variety of pyrimidine damages. In addition to the well-known photoproducts, pyrimidine dimers and 6-4'-(pyrimidin-2'one)pyrimidines, DNA sequence analysis has shown that purified E. coli endonuclease III incises broad-spectrum UV-irradiated DNA at cytosines and OsO/sub 4/-oxidized DNA at thymines. The wavelength dependence of endonuclease III incision of superhelical DNA irradiated by 250 to 320 nm. monochromatic light was examined. Maximal enzymic cleavage was obtained with substrates irradiated between 265 and 285 nm, with peak activity at 280 nm. Incision of DNA irradiated at 254 nm was reduced. Therefore, these cytosine photoproducts are optimally formed at biologically significant wavelengths and may be involved in actinic carcinogenesis. Enzymic release of modified labeled cytosine into the ethanol-soluble fraction from irradiated poly(dG-dC):poly(dG-dC) was linear with time of reaction, quantity of enzyme protein and exposure of substrate to irradiation. Identification of the cytosine UV photoproduct is currently under investigation.
Research Organization:
Temple Univ. Medical School, Philadelphia, PA
OSTI ID:
6122150
Report Number(s):
CONF-870644-
Conference Information:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
Country of Publication:
United States
Language:
English