There is a restriction endonuclease called E c o RI. What does 'co'...

Restriction endonuclease recognizes a particular palindromic sequence and degrades the same. It was so, called because it restricted the growth of bacteriophase in the bacterium ( $\mathrm{eg}, \mathrm{E}$. coli). The convention for naming these enzymes is the first letter of the name comes from the bacterial genus; the second two letters come from the species, and the fourth letter from strain, eg, Eco RI comes from Escherichia coli RY13. Roman numbers following the names indicate the order in which the enzymes were isolated.