Question

Most of the enzymes used as molecular scissors are known as restriction enzymes. What is the reason for this name?
Need help please!!

Answer 1

I believe they were initially known as 'restriction nucleases.' I suspect 'restriction enzyme' came into less rigorous conversational use and from there found its way into the literature.

Answer 2

I thought that the restriction in question was the restriction of 'phage attack on E-coli strains which have evolved the enzymes to stop 'phage killing them. There are two enzymes in the mechanism - a methylase which stops the host genome being digested by methylating bases in the recognition site and the endonuclease which digests foriegn, unmethylated DNA. In this way, viruses such as bacteriophage are stopped.

http://en.wikipedia.org/wiki/Restriction_enzymes