Purification and characterization of an endonuclease from calf thymus acting on irradiated DNA
An endonuclease acting on DNA exposed to ultraviolet light or gamma-rays was extensively purified from calf thymus. The enzyme has a pH optimum at pH 7.0 to 7.5, acts with equal efficiency in the presence of EDTA or divalent cations (Mg 2+ or Ca 2+), is inhibited by NaC1 and tRNA and is inactivated by incubation at 50 C. Its molecular weight, determined by Sephadex chromatography or SDS-gel electrophoresis, is + or - 30,000. The enzyme catalyzes the formation of single-strand breaks with 5'-phosphate termini in double-stranded DNA irradiated with ultraviolet or gamma-rays. It does not act on unirradiated DNA or denatured DNA. The enzymatic activity on ultraviolet- and gamma-irradiated DNA is associated with the same protein. The site of action of the enzyme in ultraviolet-irradiated DNA is a photoproduct other than pyrimidine dimers, and can also be induced by irradiation of the DNA in vivo. (Author) (GRA)
- Research Organization:
- Rijksverdedigingsorganisatie TNO, Rijswijk (Netherlands). Medisch Biologisch Lab. TNO
- DOE Contract Number:
- EURATOM-107-72-1-BIAN
- OSTI ID:
- 7248543
- Report Number(s):
- N-75-24340; MBL-1974-35 TDCK-65576
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
BIOLOGICAL RADIATION EFFECTS
NUCLEASES
RADIOSENSITIVITY EFFECTS
CALVES
GAMMA RADIATION
STRAND BREAKS
THYMUS
ULTRAVIOLET RADIATION
ANIMALS
BIOLOGICAL EFFECTS
BODY
CATTLE
DOMESTIC ANIMALS
ELECTROMAGNETIC RADIATION
ENZYMES
IONIZING RADIATIONS
LYMPHATIC SYSTEM
MAMMALS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PHOSPHOTRANSFERASES
RADIATION EFFECTS
RADIATIONS
RUMINANTS
TRANSFERASES
VERTEBRATES
560111* - Radiation Effects on Biochemicals- In Vitro- (-1987)