Abstract
An endonuclease which hydrolyzes thermally denatured DNA has been detected in lamb brain homogenates. A unique assay which depends on the ability of the enzyme to decrease the antigenic competence of thermally denatured DNA facilitated its detection and was used during its purification. Evidence for thermally denatured DNA being the preferred substrate was obtained by: (a) release of acid-soluble P 32, (b) loss of residual transforming activity of denatured DNA, (c) disappearance of only the denatured DNA band when partially denatured DNA was treated with the endonuclease and the mixture subjected to CsCl centrifugation, and (d) loss of serologic activity. Oligonucleotides varying in chain length from 5 to 14 residues are the products of the enzymatic digestion. By analysis of the oligonucleotide products after treatment with snake venom diesterase, the site of hydrolysis was identified as the 3′ hydroxyl side of the diester bond.
Published Version
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