By: Josh Escobar
There are two major types of nucleases: (1) exonucleases and (2) endonucleases. Exonucleases are capable of removing nucleotides one at a time from a DNA molecule whereas endonucleases work by cleaving the phosphodiester bonds within DNA molecule.1 Examples of nucleases are Bal 31, which is a double-stranded exonuclease commonly used for producing deletion sets, exonuclease I and exonuclease III for 3'-5' exonuclease activity, Dnase I, which is an endonuclease used for splitting single-stranded and double-stranded DNA molecules, and nuclease S1 capable of degrading both single-stranded DNA and RNA molecules. Different enzymes are used for manipulating DNA. One of them is a group of enzymes that promotes the hydrolysis of nucleic acids, such as DNA; others are DNA polymerases, kinases, alkaline phosphatases, and topoisomerases. Nucleases are enzymes that are capable of catalyzing hydrolysis of nucleic acids by cleaving the phosphodiester bonds between nucleotide subunits of nucleic acids. The optimum stability of the enzyme is at pH 5 and the optimum temperature is 37 °C.