Answer: <u>Endonuclease enzymes used in molecular biology that cut DNA at specified points.</u>
Explanation:
Enzymes are specific protein types which bind to a substrate within a reaction, to increase the rate of reaction within the solution- they speed up the rate of reaction.
Restriction enzymes are bacteria-derived enzymes; these make cuts on deoxyribonucleic acid molecules or DNA. These are also called restriction endonucleases. They are utilized in molecular biology for DNA cloning and sequencing and cut DNA into smaller pieces called fragments.
Restriction enzymes make directed cuts on DNA molecules. They precisely target sites on DNA to produce mostly identical or homogenous, discrete fragments of equal sizes, producing blunt or sticky ends. In order to do this, they recognize sequences of nucleotides that correspond with a complementary sequence on the endonuclease called restriction sites.
There are several kinds that may require cofactors (chemical or metallic compounds that aid in enzyme activity) :
- Type I: cleave far away from the recognition site; require ATP and SAMe S-Adenosyl-L-Methionine
- Type II: cleave near to the site; require Magnesium
- Type III: cleave near to the site; require ATP which is not hydrolysed but SAMe S-Adenosyl-L-Methionine is optional
- Type IV: cleavage targeted to DNA that have undergone post transcriptional modification through certain types of methylation (addition of a methyl group)
