Nomenclature of restriction enzymes consists three parts:
Indicates the genus and species of specific organism by using abbreviation into three letters. EXAMPLE: Eco is for Escherichia coli; here first letter ‘E’ is for genus whereas last two letters ‘co’ is for species.
Indicates the strain of the relevant species by using a letter, number or its combination.
Indicate specific restriction modification systems present in the same organism or strain by using a roman numeral.
EXAMPLE: the name of EcoRI restriction enzyme is derived as:
E : Escherichia (genus)
co : coli (species)
R : RY13 (strain)
I : first identified in the bacterium