Nomenclature
There have been numerous identifications of restriction enzymes since their discovery in the 1970s; for instance, more than 3500 distinct Type II restriction enzymes have been characterized. Using a naming scheme based on bacterial genus, species, and strain, each enzyme is named after the bacterium from which it was obtained.
For example, the EcoRI restriction enzyme’s name
Derivation of the EcoRI |
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Abbreviation | E | co | R | I |
Meaning | Escherichia | Coli | RY13 | First Identified |
Description | Genus | Specific Species | Strain | Order of Identification |
Restriction Enzymes
Restriction enzyme is a bacterial protein that cleaves DNA at particular locations, these sites are called restricted sites. The restriction enzymes guard against bacteriophages in living bacteria. They identify the bacteriophage and cleave it at its restriction sites, destroying its DNA. Important genetic engineering tools include restriction enzymes. They may be separated from bacteria and applied in research facilities. The recognition sequences, or short and distinct nucleotide sequences, are recognized by restriction enzymes in DNA. When a DNA sequence is recognized by the restriction enzyme, it hydrolyzes the bond between neighboring nucleotides and cleaves the DNA molecule. The bacteria use the enzyme methylases to add the methyl group at the adenine or cytosine bases within the recognition sequence, preventing the DNA sequences from disintegrating.