What are restriction 2 enzymes?
Type II restriction enzymes are the familiar ones used for everyday molecular biology applications such as gene cloning and DNA fragmentation and analysis. These enzymes cleave DNA at fixed positions with respect to their recognition sequence, creating reproducible fragments and distinct gel electrophoresis patterns.
What are type II restriction endonucleases?
Type II restriction endonucleases are components of restriction modification systems that protect bacteria and archaea against invading foreign DNA. Most are homodimeric or tetrameric enzymes that cleave DNA at defined sites of 4-8 bp in length and require Mg2+ ions for catalysis.
What sequence does Ava II cut?
We have determined that the type II restriction enzyme Ava II, isolated from Anabaena variabilis, recognizes and cuts the sequence 5′ – G↓GTCC – 3′ 3′ – CCAG↑G – 5′ The eight Ava II sites of pBR322 have been mapped, as well as a unique site for Ava I. I.
How do Type 2 restriction enzymes work?
More than 3000 type II restriction endonucleases have been discovered. They recognize short, usually palindromic, sequences of 4–8 bp and, in the presence of Mg2+, cleave the DNA within or in close proximity to the recognition sequence. The orthodox type II enzymes are homodimers which recognize palindromic sites.
How many restriction sites are there for Ava II in the plasmid?
eight Ava II sites
We have determined that the type II restriction enzyme Ava II, isolated from Anabaena variabilis, recognizes and cuts the sequence (formula: see article). The eight Ava II sites of pBR322 have been mapped, as well as a unique site for Ava I.
What is the natural function of type 2 restriction enzymes?
Restriction endonucleases occur ubiquitously among prokaryotic organisms (1,2). Their principal biological function is the protection of the host genome against foreign DNA, in particular bacteriophage DNA (3).
Where do Type 2 restriction enzymes cut?
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.
Why is pUC19 a good cloning vector?
pUC19 is a commonly used cloning vector that conveys the Amp resistance. The molecule is a small double-stranded circle, 2686 base pairs in length, and has a high copy number. NEB offers a selection of common cloning plasmids and DNAs for use as substrates.
What is the structure of a type II restriction enzyme?
The orthodox type II enzymes are homodimers which recognize palindromic sites. Depending on particular features subtypes are classified. All structures of restriction enzymes show a common structural core comprising four β-strands and one α-helix.
How does a type II restriction endonuclease work?
The orthodox type II restriction endonuclease is a homodimer of ∼2 × 30 kDa molecular mass, which recognizes a palindromic sequence 4–8 bp in length, and in the presence of Mg 2+ cleaves the two strands of the DNA within or immediately adjacent to the recognition site to give a 5′-phosphate and a 3′-OH end.
Can a Avai isoschizomer Digest 1 μg of plasmid DNA?
BsoBI, a thermophilic AvaI isoschizomer, is alsoavailable. This enzyme has shown to have lower activity on some supercoiledplasmids, with more than 1 unit required to digest 1 μg plasmid DNA. Forcomplete digestion of 1 μg of plasmid DNA please follow our recommendeddigestion protocol.
Which is E coli strain carries the avai gene?
An E. coli strain that carries the AvaI gene from Anabaena variabilis (ATCC 27892). One unit is defined as the amount of enzyme required to digest 1 µg of λ DNA in 1 hour at 37°C in a total reaction volume of 50 µl.