type II restriction enzyme

References

type II restriction enzyme

biology

Also known as: type II restriction endonuclease

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Last updated

July 14, 2026

Quick Summary

Type II restriction enzymes are proteins produced by bacteria that cut DNA at specific recognition sites. These enzymes are crucial for genetic engineering and recombinant DNA technology because they allow scientists to precisely cut and manipulate DNA fragments.12

Unlike other types of restriction enzymes, Type II enzymes cleave DNA directly within their recognition sites, which are typically short sequences of four to eight nucleotide bases. Bacteria use restriction enzymes as a defense mechanism against invading viruses, such as bacteriophages, by degrading foreign DNA.1

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nucleic acid
Nucleases
Type II restriction endonucleases always cleave at or near their recognition sites. They produce small, well-defined fragments of DNA that help to characterize genes and genomes and that produce recombinant DNAs. Fragments of DNA produced by restriction endonucleases can be moved from one organism to…
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Type II restriction endonucleases always cleave at or near their recognition sites. They produce small, well-defined fragments of DNA that help to characterize genes and genomes and that produce recombinant DNAs. Fragments of DNA produced by restriction endonucleases can be moved from one organism to…
Read More

genetic engineering
Historical developments
Smith purified so-called type II restriction enzymes, which were found to be essential to genetic engineering for their ability to cleave a specific site within the DNA, owing to their ability to recognize particular nucleotide sequences and therefore cut DNA at predictable locations (as opposed to type I…
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Smith purified so-called type II restriction enzymes, which were found to be essential to genetic engineering for their ability to cleave a specific site within the DNA, owing to their ability to recognize particular nucleotide sequences and therefore cut DNA at predictable locations (as opposed to type I…
Read More

recombinant DNA
Invention of recombinant DNA technology
Smith subsequently identified type II restriction enzymes. Unlike type I restriction enzymes, which cut DNA at random sites, type II restriction enzymes cleave DNA at specific sites; hence, type II enzymes became important tools in genetic engineering.
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Smith subsequently identified type II restriction enzymes. Unlike type I restriction enzymes, which cut DNA at random sites, type II restriction enzymes cleave DNA at specific sites; hence, type II enzymes became important tools in genetic engineering.
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restriction enzyme
Type II restriction enzymes also differ from types I and III in that they cleave DNA at specific sites within the recognition site; the others cleave DNA randomly, sometimes hundreds of bases from the recognition sequence. Several thousand type II restriction enzymes have been identified…
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Type II restriction enzymes also differ from types I and III in that they cleave DNA at specific sites within the recognition site; the others cleave DNA randomly, sometimes hundreds of bases from the recognition sequence. Several thousand type II restriction enzymes have been identified…
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Hamilton O. Smith
…what came to be called type II restriction enzymes. These enzymes not only recognize a specific region in a DNA sequence but always cut the DNA at that very site. This predictable behaviour made type II restriction enzymes valuable tools in the study of DNA structure and in recombinant DNA…
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…what came to be called type II restriction enzymes. These enzymes not only recognize a specific region in a DNA sequence but always cut the DNA at that very site. This predictable behaviour made type II restriction enzymes valuable tools in the study of DNA structure and in recombinant DNA…
Read More