DPN I

In PCR-mediated mutagenesis, DpnI nuclease has been used for the digestion of wild type DNA after PCR.

Isoschizomers
The enzyme is an isoschizomer to Bsp143 I, Dpn II, Mbo I, Nde II and Sau3A I.
Methylation sensitivity
The enzyme is only inhibited by the occurrence of 5-methylcytosine at the indicated site (*) if no 6-methyladenine is present.
Typical ligation and recutting assay
Dpn I fragments obtained by complete digestion of 1μg pBR322 DNA are ligated for 16 hours at +4°C with 1U T4 DNA Ligase in 10μl buffer that contains 66mM Tris-HCl, 5mM MgCl₂, 5mM Dithiothreitol, 1mM ATP, pH 7.5 (at +20°C). The percentages of product that can be ligated and subsequently recut with Dpn I (yielding the typical pattern of pBR322 × Dpn I fragments) are stated under "Lig" and "Rec" in the certificate of analysis.