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1 July 2003 Long-Lived Mutagenic Radicals Induced in Mammalian Cells by Ionizing Radiation are Mainly Localized to Proteins
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Abstract

Kumagai, J., Masui, K., Itagaki, Y., Shiotani, M., Kodama, S., Watanabe, M. and Miyazaki, T. Long-Lived Mutagenic Radicals Induced in Mammalian Cells by Ionizing Radiation are Mainly Localized to Proteins. Radiat. Res. 160, 95–102 (2003).

We have provided evidence that long-lived radicals, produced by ionizing radiation, are highly mutagenic and transforming in mammalian cells. Long-lived radicals are scavenged effectively by vitamin C or by epigallocatechin-3-O-gallate (EGCG). Long-lived radicals are not involved in lethality or in the induction of chromosome aberrations. We now report the results of experiments that define the relative amounts of long-lived radicals in DNA and proteins and identify the major protein radicals as sulfinyl radicals (R-CH2-S-O·). To make these assignments, yields of long-lived radicals in γ-irradiated salmon sperm DNA and albumin were compared by ESR. ESR spectra of long-lived radicals produced in irradiated Syrian hamster embryo (SHE) cells were analyzed precisely and compared with ESR parameters obtained by density functional theory calculations. Long-lived radicals yields of 99.8% were produced in proteins. We also identified a new type of long-lived radical as H-added phenylalanine radicals. While our evidence does not rule out the possibility of important biological consequences of the low-level long-lived radicals created by radiation, it implicates radicals in proteins as playing a key role in genetic effects of ionizing radiation. We suggest that these novel radicals, wherever they reside, need to be considered in explanations of biological sequela of radiation.

Jun Kumagai, Kiyonao Masui, Yoshiteru Itagaki, Masaru Shiotani, Seiji Kodama, Masami Watanabe, and Tetsuo Miyazaki "Long-Lived Mutagenic Radicals Induced in Mammalian Cells by Ionizing Radiation are Mainly Localized to Proteins," Radiation Research 160(1), (1 July 2003). https://doi.org/10.1667/RR3015
Received: 20 April 2002; Accepted: 1 March 2003; Published: 1 July 2003
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