Tools of Recombinant DNA Technology

Abstract

Restriction endonucleases, also called restriction enzymes, are bacterial proteins that cut the long, linear DNA molecule into fragments. Restriction enzymes are a major tool of recombinant DNA technology. A restriction enzyme recognizes a specific nucleotide sequence, such as AGCT, and cuts DNA wherever that combination of “letters” occurs. These enzymes are isolated from bacteria and named with a three- or four-letter sequence followed by a roman numeral. For example, EcoRI is a restriction enzyme isolated from Escherichia coli.