4) Mung bean nuclease:
As the name suggest, this nuclease enzyme is isolated from mung bean sprouts (Vigna radiata). Mung bean nuclease enzymes can degrade single stranded DNA as well RNA. Under high enzyme concentration, they can degrade double stranded DNA, RNA or even DNA/RNA hybrids.
Mung bean nuclease can cleave single stranded DNA or RNA to produce 5'-phosphoryl mono and oligonucleotides. It requires Zn2+ ion for its activity and shows optimal activity at 37°C. The enzyme works in low salt concentration (25mM ammonium acetate) and acidic pH (pH 5.0). Treatment with EDTA or SDS results in irreversible inactivation of the enzyme.
Mung bean nuclease is less robust than S1 nuclease and easier to handle. It has been used to create blunt end DNA by cleaving protruding ends from 5' ends. This enzyme cannot produce nicks in a double stranded DNA but at higher concentration, it can generate nicks and cleave double stranded DNA.
Bibliography:
- Boyer P. D. 1981. The Enzymes . Academic press Inc Ltd.
- Heppel L.A., Singer M.F., Hilmoe R.J. 1962. The mechanism of action of polynucleotide phosphorylase; Annals New York Academy of Sciences.
- http://openi.nlm.nih.gov/detailedresult.php?img=3071783_1423-0127-18-23-3&req=4
- Mohanty B.K , Kushner S.R. 2000. Polynucleotide phosphorylase functions both as a 3′ → 5′ exonuclease and a poly(A) polymerase in Escherichia coli ; PNAS; 97:11966-11971 .
- Singer M.F., Hilmoe R.J. and Manago M.G. 1960. Studies on t he mechanism of action of polynucleotide. J.Bio Chem 236 (9).