How are restriction enzymes named conventionally?

First letter from the genus name, followed by the species name

b) First letter from the genus name, followed by the species name.

Restriction enzymes are named using a convention where the first letter of the name comes from the genus name, and the second and third letters come from the species name of the prokaryotic cell from which they were isolated. For example, EcoRI comes from Escherichia coli RY 13, where "Eco" is derived from Escherichia coli and "RI" indicates the order in which the enzyme was isolated from that strain of bacteria.