Effect of. gamma. -irradiated DNA on the activity of DNA polymerase. [/sup 60/Co]
A cell-free assay was developed to measure the effect of ..gamma..-irradiated DNA template on the ability of DNA polymerase to copy unirradiated template. Doses as low as 1 krad were able to decrease (approx. 15%) the activity of both bacterial and mammalian DNA polymerases in the assay. The percentage of polymerase activity decreased as the dose received by the template increased. The reduction in DNA polymerase activity was shown to be due to an inhibition of the enzyme by the irradiated DNA. Irradiated poly(dA-dT) was more effective in reducing polymerase activity than calf thymus DNA. Thus the polymerase-inhibition site(s) appears to be associated with base damage, specifically adenine or thymine. Using a free-radical scavenger, OH radicals were found to be involved in producing the damage sites. The interaction between irradiated DNA and DNA polymerase was found to be specific for the enzyme and not for other proteins present in the assay. The inhibition of DNA polymerase occurred prior to or during the initiation of DNA synthesis rather than after initiation of synthesis, i.e., during elongation.
- Research Organization:
- Univ. of California, Los Angeles
- OSTI ID:
- 6318450
- Journal Information:
- Radiat. Res.; (United States), Vol. 86:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
BIOLOGICAL RADIATION EFFECTS
ENZYME ACTIVITY
INHIBITION
POLYMERASES
ADENINES
COBALT 60
DOSE-RESPONSE RELATIONSHIPS
GAMMA RADIATION
HYDROXYL RADICALS
MICROCOCCUS LUTEUS
THYMINE
THYMUS
AMINES
ANTIMETABOLITES
AZINES
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BODY
COBALT ISOTOPES
DRUGS
ELECTROMAGNETIC RADIATION
ENZYMES
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LYMPHATIC SYSTEM
MICROCOCCUS
MICROORGANISMS
MINUTES LIVING RADIOISOTOPES
NUCLEI
NUCLEIC ACIDS
NUCLEOTIDYLTRANSFERASES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PHOSPHORUS-GROUP TRANSFERASES
PURINES
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOISOTOPES
TRANSFERASES
URACILS
YEARS LIVING RADIOISOTOPES
560110* - Radiation Effects on Biochemicals- (-1987)