Gamma endonuclease of Micrococcus luteus: action on irradiated DNA.
Radiat Res
; 114(3): 556-66, 1988 Jun.
Article
em En
| MEDLINE
| ID: mdl-3375442
ABSTRACT
Gamma endonuclease is a Mg2+-independent enzyme of Micrococcus luteus that recognizes and cleaves DNA at a variety of altered pyrimidines produced by ionizing radiation. The production of enzyme-recognizable sites (ERS) by ionizing radiation under different irradiation conditions was measured. Ionizing radiation produced the greatest number of ERS when irradiations were performed under anoxic conditions in the presence of the free radical scavenger KI. Since dihydrothymine is a major pyrimidine lesion produced in DNA during anoxic irradiation, the ability of gamma endonuclease to excise this lesion was assessed. Dihydrothymine was released from DNA irradiated under anoxic conditions in a radiation dose-dependent manner, consistent with gamma endonuclease's known DNA glycosylase activity. Gamma endonuclease was also shown to cleave heavily uv-irradiated DNA. When the sequence specificity of gamma-endonuclease cleavage was studied using uv-irradiated DNA, cleavage was seen specifically at cytosines. The identity of this enzyme-recognizable cytosine photoproduct is not known.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
DNA Super-Helicoidal
/
Endodesoxirribonucleases
/
Micrococcus
Idioma:
En
Revista:
Radiat Res
Ano de publicação:
1988
Tipo de documento:
Article