Endonuclease III: An Endonuclease from Escherichia coli That Introduces Single Polynucleotide Chain Scissions in Ultraviolet-Irradiated DNA
An endonuclease that makes single polynucleotide chain scissions in UV-irradiated DNA has been purified from Escherichia coli. The activity has the following properties: (1) unirradiated DNA is attacked very little if at all; (2) single-stranded DNA is not attacked, whether irradiated or not; (3) there is no requirement for divalent cations, and the activity is not affected by the addition of EDTA; (4) the pH optimum is approximately 7; (5) the activity is inhibited by 1 M NaC1, single-stranded DNA, transfer RNA, and unirradiated double-stranded DNA; (6) the sedimentation coefficient, S 20, W’ is approximately 2.6; (7) it is a basic protein. The enzyme is tentatively named E. coli endonuclease III. The physiological function of the endonuclease has not yet been established.
KeywordsVelocity Sedimentation Sedimentation Analysis Exponential Gradient Alkaline Sucrose Gradient Typical Reaction Mixture
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