Enzyme Taxonomy

Type I endonucleases have both restriction (cutting) and modification (methylation) activity, require ATP to function, and cut at random 1000 or more nucleotides away from a specific recognition sequence.

Type II endonucleases have only restriction activity, cut at a site within or adjacent to the recognition sequence, and require a cofactor such as a magnesium ion (Mg++) rather than ATP to function.

Type III endonucleases have both restriction and modifying activity, require ATP, and cut at specific sites near the recognition sequence, but these sites are difficult to predict.

Consequently, Type II endonucleases are the most useful and common in recombinant DNA research.
 
 
 
Nomenclature of the Restriction Endonuclease (Enzyme) EcoR1
E Genus
Escherichia
co
species
coli
R
strain
RY13
1
order of enzyme isolation
1st enzyme isolated