RESTRICTION ENDONUCLEASE

WordNet Dictionary

	Definition:	[n] 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 technology

	Sponsored Links:

	Synonyms:	restriction enzyme, restriction nuclease

	See Also:	endonuclease

Biology Dictionary

	Definition:	A protein that recognizes specific, short nucleotide sequences and cuts DNA at those sites. Bacteria contain over 400 such enzymes that recognize and cut over 100 different DNA sequences.

Glossary

	Definition:	A class of endonucleases that cleaves DNA after recognizing a specific sequence, such as BamH1 (GGATCC), EcoRI (GAATTC), and HindIII (AAGCTT). Type I. Cuts nonspecifically a distance greater than 1000 bp from its recognition sequence and contains both restriction and methylation activities. Type II. Cuts at or near a short, and often symmetrical, recognition sequence. A separate enzyme methylates the same recognition sequence. Type III. Cuts 24-26 bp downstream from a short, asymmetrical recognition sequence. Requires ATP and contains both restriction and methylation activities.