InterPro domain: IPR003154

This family summarizes both S1 and P1 nucleases ( 3.1.30.1 ) which cleave RNA and single stranded DNA with no base specificity [ 1 ]. S1 nuclease is more active on DNA than RNA. Its reaction products are oligonucleotides or single nucleotides with 5' phosphoryl groups [ 2 ]. Although its primary substrate is single-stranded, it may also introduce single-stranded breaks in double-stranded DNA or RNA, or DNA-RNA hybrids. It is used as a reagent in nuclease protection assays and in removing single stranded tails from DNA molecules to create blunt ended molecules and opening hairpin loops generated during synthesis of double stranded cDNA. P1 nuclease cleaves its substrate at every position yielding nucleoside 5' monophosphates, and it does not recognize or act on double-stranded DNA [ 3 ]. It is useful at removing single stranded strands hanging off the end of double stranded DNA and at completely cleaving melted DNA for simple DNA composition analysis.

1. Single-strand-specific nucleases. FEMS Microbiol. Rev. 26, 457-91
2. S1 nuclease of Aspergillus oryzae. Gene Amplif Anal 2, 205-15
3. Recognition of single-stranded DNA by nuclease P1: high resolution crystal structures of complexes with substrate analogs. Proteins 32, 414-24