Micrococcal nuclease

Micrococcal Nuclease (S7 Nuclease) is an endo-exonuclease that preferentially digests single-stranded nucleic acids.The rate of cleavage is 30 times greater at the 5' side of A or T than at G or C and results in the production of mononucleotides and oligonucleotides with terminal 3'-phosphates. The enzyme is also active against double-stranded DNA and RNA and all sequences will be ultimately cleaved.

Characteristics
The enzyme has a molecular weight of 16.9kDa.

The pH optimum is reported as 9.2. The enzyme activity is strictly dependent on Ca2+ and the pH optimum varies according to Ca2+ concentration. The enzyme is therefore easily inacitvated by EDTA.

Source
This enzyme is the extracellular nuclease of Staphylococcus aureus. Two strains, V8 and Foggi, yield almost identical enzymes. A common source is E.coli cells carrying a cloned nuc gene encoding Staphylococcus aureus extracellular nuclease (micrococcal nuclease).

Applications

 * Hydrolysis of nucleic acids in crude cell-free extracts.
 * Sequencing of RNA.
 * Preparation of rabbit reticulocytes lysates
 * Studies of chromatin structure.
 * Remove nucleic acids from protein preparation allowing for folding and structure-function studies.