restriction enzyme

restriction enzyme

noun

Definition of RESTRICTION ENZYME

: any of various enzymes that cleave DNA into fragments at specific sites in the interior of the molecule —called also restriction endonuclease

First Known Use of RESTRICTION ENZYME

1965

restriction enzyme

noun    (Medical Dictionary)

Medical Definition of RESTRICTION ENZYME

: any of various enzymes that cleave DNA into fragments at specific sites in the interior of the molecule and are often used as tools in molecular analysis

restriction enzyme

noun    (Concise Encyclopedia)

Protein (more specifically, an endonuclease) produced by bacteria that cleaves DNA at specific sites along its length. Thousands have been found, from many different bacteria; each recognizes a specific nucleotide sequence. In the living bacterial cell, these enzymes destroy the DNA of certain invading viruses (bacteriophages), thus placing a “restriction” on the number of viral strains that can cause infection; the bacterium's own DNA is protected from cleavage by methyl (CH) groups, which are added by enzymes at the recognition sites to mask them. In the laboratory, restriction enzymes allow researchers to isolate DNA fragments of interest, such as those that contain genes, and to recombine them with other DNA molecules; for this reason they have become very powerful tools of recombinant DNA biotechnology (see DNA recombination).