restriction endonucleases
(= restriction enzymes)
Class of bacterial enzymes that cut DNA at specific sites. In bacteria their function is to destroy foreign DNA, such as that of bacteriophages (host DNA is specifically modified at these sites). Type I restriction endonucleases occur as a complex with the methylase and a polypeptide that binds to the recognition site on DNA. They are often not very specific and cut at a remote site. Type II restriction endonucleases are the classic experimental tools. They have very specific recognition and cutting sites. The recognition sites are short, 4-8 nucleotides, and are usually palindromic sequences. Because both strands have the same sequence running in opposite directions the enzymes make double-stranded breaks, which, if the site of cleavage is off-centre, generates fragments with short single-stranded tails; these can hybridize to the tails of other fragments and are called sticky ends. They are generally named according to the bacterium from which they were isolated (first letter of genus name and the first two letters of the specific name). The bacterial strain is identified next and multiple enzymes are given Roman numerals. For example the two enzymes isolated from the R strain of E. coli are designated Eco RI and Eco RII.

Dictionary of molecular biology. 2004.

Look at other dictionaries:

  • restriction endonucleases — restriction endonucleases. См. рестрикционная эндонуклеаза. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Restriction enzyme — Glossary Restriction …   Wikipedia

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  • Restriction digest — A restriction digest is a procedure used in molecular biology to prepare DNA for analysis or other processing. It is sometimes termed DNA fragmentation (this term is used for other procedures as well). Hartl and Jones describe it this way: This… …   Wikipedia

  • Restriction endonuclease — An enzyme from bacteria that can recognize specific base sequences in DNA and cut (restrict) the DNA at that site (the restriction site). Also called a restriction enzyme. * * * restriction endonuclease n RESTRICTION ENZYME * * * see restriction… …   Medical dictionary

  • restriction fragment length polymorphism — Abbreviation: RFLP A class of genetic marker based on the detection of variation in the length of restriction fragments generated when DNA is treated with restriction endonucleases. Differences in fragment lengths arise due to genetic variation… …   Glossary of Biotechnology

  • restriction map — Map of DNA showing the position of sites recognized and cut by various restriction endonucleases …   Dictionary of molecular biology

  • restriction fragment — A shortened DNA molecule generated by the cleavage of a larger molecule by one or more restriction endonucleases …   Glossary of Biotechnology

  • Restriction modification system — The restriction modification system (RM system) is used by bacteria, and perhaps other prokaryotic organisms to protect themselves from foreign DNA, such as bacteriophages. This phenomenon was first noticed in the 1950s. Certain bacteria strains… …   Wikipedia

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