10 information about Restriction Enzymes (Molecular Scissor)
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10 information about Restriction Enzymes (Molecular Scissor)
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A restriction enzyme is an enzyme isolated from bacteria that cuts DNA molecules at specific sequences. The isolation of these enzymes was critical to the development of recombinant DNA (rDNA) technology and genetic engineering.
restriction enzyme, also called restriction endonuclease, a protein produced by bacteria that cleaves DNA at specific sites along the molecule. In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms.
Today, scientists recognize three categories of restriction enzymes: type I, which recognize specific DNA sequences but make their cut at seemingly random sites that can be as far as 1,000 base pairs away from the recognition site; type II, which recognize and cut directly within the recognition site; and type III, ...
Approximately 3,000 restriction enzymes, recognizing over 230 different DNA sequences, have been discovered. They have been found mostly in bacteria, but have also been isolated from viruses, archaea and eukaryotes.
The function of restriction endonucleases is mainly protection against foreign genetic material especially against bacteriophage DNA. The other functions attributed to these enzymes are recombination and transposition.
The restriction enzyme is a protein produced by bacteria that cleaves the DNA at specific sites. This site is known as the restriction site. The restriction enzymes protect the live bacteria from bacteriophages. They recognize and cleave at the restriction sites of the bacteriophage and destroy its DNA.
Most restriction enzymes recognize sequences of four to eight base pairs and hydrolyze a single phosphodiester bond on each strand. A characteristic of many of these cleavage or restriction sites is their double rotational symmetry. Generally, the cleavage sites are symmetrically positioned, or palindromic.