restriction enzyme

n. Any of a group of enzymes that catalyze the cleavage of DNA at specific sites to produce discrete fragments, used especially in genetic engineering. Also called restriction endonuclease.

restriction enzyme

n (Biochemistry) any of several enzymes produced by bacteria as a defence against viral infection and commonly used to cut DNA for genetic manipulation or diagnosis

restric′tion en`zyme

n. any of a group of enzymes that are capable of cutting DNA at specific sites along its strand. [1960–65]

Thesaurus

Noun

restriction enzyme - any of the enzymes that cut nucleic acid at specific restriction sites and produce restriction fragments; obtained from bacteria (where they cripple viral invaders); used in recombinant DNA technologyrestriction endonuclease, restriction nucleaseendonuclease - a nuclease that cleaves nucleic acids at interior bonds and so produces fragments of various sizes

Restriction enzyme

An enzyme, specifically an endode-oxyribonuclease, that recognizes a short specific sequence within a deoxyribonucleic acid (DNA) molecule and then catalyzes double-strand cleavage of that molecule. Restriction enzymes have been found only in bacteria, where they serve to protect the bacterium from the deleterious effects of foreign DNA. See Deoxyribonucleic acid (DNA)

There are three known types of restriction enzymes. Type I enzymes recognize a specific sequence on DNA, but cleave the DNA chain at random locations with respect to this sequence. They have an absolute requirement for the cofactors adenosine triphosphate (ATP) and S-adenosylmethionine. Because of the random nature of the cleavage, the products are a heterogeneous array of DNA fragments. Type II enzymes also recognize a specific nucleotide sequence but differ from the type I enzymes in that they do not require cofactors and they cleave specifically within or close to the recognition sequence, thus generating a specific set of fragments. It is this exquisite specificity which has made these enzymes of great importance in DNA research, especially in the production of recombinant DNAs. Type III enzymes have properties intermediate between those of the type I and type II enzymes. They recognize a specific sequence and cleave specifically a short distance away from the recognition sequence. They have an absolute requirement for the ATP cofactor, but they do not hydrolyze it.

A key feature of the fragments produced by restriction enzymes is that when mixed in the presence of the enzyme DNA ligase, the fragments can be rejoined. Should the new fragment carry genetic information that can be interpreted by the bacterial cell containing the recombinant molecule, then the information will be expressed as a protein and the bacterial cell will serve as an ideal source from which to obtain that protein. For instance, if the DNA fragment carries the genetic information encoding the hormone insulin, the bacterial cell carrying that fragment will produce insulin. By using this method, the human gene for insulin has been cloned into bacterial cells and used for the commercial production of human insulin. The potential impact of this technology forms the basis of the genetic engineering industry. See Enzyme, Genetic engineering

restriction enzyme

re·stric·tion en·do·nu·cle·ase

one of many endonucleases isolated from bacteria that cleave or hydrolyze (cut) foreign double-stranded DNA chains at specific recognition sites defined by DNA sequences; these endonucleases have become standard laboratory devices for making specific cuts in DNA as a first step in deducing sequences and are sometimes referred to as a "chemical knife," usually named by a three- or four-letter abbreviation of the name of the organism from which isolated (for example, EcoB from Escherichia coli, strain B). Synonym(s): restriction enzyme

restriction enzyme

n. Any of a group of enzymes that catalyze the cleavage of DNA at specific sites to produce discrete fragments, used especially in genetic engineering. Also called restriction endonuclease.

re·stric·tion en·do·nu·cle·ase

(rĕ-strik'shŭn en'dō-nū'klē-ās) One of many endonucleases isolated from bacteria that hydrolyze (cut) double-stranded DNA chains at specific sequences, thus inactivating a foreign (viral or other) DNA and restricting its activity; standard laboratory devices for making specific cuts in DNA as a first step in deducing sequences.
Synonym(s): restriction enzyme.

restriction enzyme

One of the many enzymes that break DNA at specific sites. These enzymes are extensively used in research and in GENETIC ENGINEERING. Also known as restriction endonucleases.

restriction enzyme

restriction endonuclease

an endonuclease that recognizes a specific DNA base sequence (recognition sequence, recognition site, restriction sequence or restriction site) and cleaves both strands of DNA at or near that site. The enzyme cuts the DNA, generating restriction fragments with OVERHANGING ENDS or BLUNT ENDS. See also COHESIVE ENDS.

restriction enzyme

restriction enzyme

restriction enzyme

restric′tion en`zyme

Restriction enzyme

Restriction enzyme

restriction enzyme

re·stric·tion en·do·nu·cle·ase

restriction enzyme

re·stric·tion en·do·nu·cle·ase

restriction enzyme

restriction enzyme

restriction endonuclease

restriction enzyme

Synonyms for restriction enzyme

noun any of the enzymes that cut nucleic acid at specific restriction sites and produce restriction fragments

Synonyms

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