Nuclease P1 (Nuclease 5'-Nucleotidehydrolase, 3'-Phosphohydrolase) from Penicillium citrinum, a zinc dependent glyco-enzyme consisting of 270 amino acid residues, hydrolyzes both 3'-5'-phosphodiester bonds in RNA and heat denatured DNA and 3'-phosphomonoester bonds in mono- and oligonucleotides terminated by 3'-phosphate without base specificity. Nuclease P1 is capable of hydrolyzing single stranded DNA and RNA completely to the level of mononucleoside 5-monophosphates. The enzyme does not attack double-stranded nucleic acids, especially in the presence of more than 400mM of sodium chloride at pH 6.0. Activity: > 300U/mg protein using RNA substrate Unit Definition: One unit of nuclease activity is defined as the amount of enzyme that produces 1umole of acid soluble nucleotides from RNA based on E = 10,600 for RNA hydrolysates per minute at 37 �C, pH 5.3.