Introduction of restriction enzymes
The restriction enzyme, also known as restriction endonuclease, is an enzyme produced by bacteria that cleaves DNA at certain points throughout the molecules. Within the bacterial cell, restriction enzymes cut the DNA of foreign organisms, thereby eliminating the infecting organisms. Restriction enzymes are removed from bacteria and then used in the laboratory to alter DNA fragments like ones that contain genes and genes; this is why they are essential tools in recombinant genetic engineering ( genetic engineering).
A bacterium uses the limitation restriction enzymes
A bacterium uses the limitation enzyme to defend itself against the bacterial viruses known as bacteriophages, also known as phages. If bacteria infect a phage, it engrafts its DNA inside the bacterium’s cell to allow it to be reproduced. The restriction enzyme blocks the replication of the phage’s DNA by slicing it into several pieces. They are named after their capability to limit or limit the variety of bacteriophages that the bacterium could infect.
Each restriction enzyme can recognize an extremely short, particular pattern of nucleotide bases (the four chemical subunits of the double-stranded DNA molecules: adenine, cytosine, and thymine and guanine). These regions are known as recognition sequences, also known as recognition sites, scattered across the DNA. Different bacteria species create restricting enzymes that recognize various nucleotide sequences.
Suppose a restriction endonuclease can recognize an identifier. In that case, it cuts through the DNA molecule, activating hydrolysis (splitting of the chemical bond through the addition of a water molecule) in the bond that is formed between two adjacent nucleotides. Bacteria protect their DNA from degrading by concealing the sequences they recognize. Methylases, enzymes known as methylases, can add the methyl group (–CH 3) to cytosine or adenine bases in the recognition sequence. It is altered and shielded from endonuclease. The restriction enzyme and its corresponding methylase constitute the restriction-modification system of a bacterial species.
Four kinds of restriction enzymes
Typically, four kinds of restriction enzymes are identified and are designated as I, II, and IV. These differ in their structure, cleavage site specificity, and cofactors. Typs III and I enzymes are alike in that both restriction and methylase activity are accomplished through a large complex of enzymes.
They are not the same as Type II, where the restriction enzyme is not dependent on its methylase. Type II enzymes for restriction also differ from types I and III by cleaving DNA at specific spots in the recognition site.
Other enzymes cleave DNA randomly and sometimes hundreds of bases within their recognition sequence. A few thousand restriction enzymes of type II have been discovered in various bacteria.
These enzymes can recognize up to a couple hundred distinct sequences that are generally between four and eight bases long.
The restriction enzymes of Type IV cleave only methylated DNA and exhibit low specificity for the sequence.
Restriction enzymes were first discovered and identified in the late 1960s and into the early 1970s by molecular biologists Werner Arber, Hamilton O. Smith, and Daniel Nathans.
The capacity of these enzymes that cut DNA in precisely-placed locations helped researchers identify gene-containing fragments and combine these fragments into other molecules made of DNA–i.e., to make copies of genes.
The names for restriction enzymes come from the species, genus, or species, and the strain names for the bacteria that manufacture these enzymes. For example, EcoRI, an enzyme EcoRI, comes from the genus EcoRI. It is made from Escherichia coli strain RY13. It is believed that the restriction enzymes came from an ancestral protein common to all, which evolved to detect particular sequences via processes like gene amplification and genetic recombination.