What is "dna ligase"

ligase \ligase\ n. (Biochem.) An enzyme which catalyzes creation of a covalent bond between two substrates, resulting in a larger product which is a combination of the two starting materials; especially, DNA ligase, an enzyme which creates a phosphate bond between 5' and 3' ends of a DNA chain, resulting in a longer chain of DNA. DNA ligase is important in normal biosynthesis of DNA in the replication cycle of cells.

In molecular biology, DNA ligase is a specific type of enzyme, a ligase, that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. It plays a role in repairing single-strand breaks in duplex DNA in living organisms, but some forms (such as DNA ligase IV) may specifically repair double-strand breaks (i.e. a break in both complementary strands of DNA). Single-strand breaks are repaired by DNA ligase using the complementary strand of the double helix as a template, with DNA ligase creating the final phosphodiester bond to fully repair the DNA.

DNA ligase is used in both DNA repair and DNA replication (see Mammalian ligases). In addition, DNA ligase has extensive use in molecular biology laboratories for recombinant DNA experiments (see Applications in molecular biology research). Purified DNA ligase is used in gene cloning to join DNA molecules together to form recombinant DNA.

DNA ligase (NAD+) (, polydeoxyribonucleotide synthase (NAD), polynucleotide ligase (NAD), DNA repair enzyme, DNA joinase, polynucleotide synthetase (nicotinamide adenine dinucleotide), deoxyribonucleic-joining enzyme, deoxyribonucleic ligase, deoxyribonucleic repair enzyme, deoxyribonucleic joinase, DNA ligase, deoxyribonucleate ligase, polynucleotide ligase, deoxyribonucleic acid ligase, polynucleotide synthetase, deoxyribonucleic acid joinase, DNA-joining enzyme, polynucleotide ligase (nicotinamide adenine dinucleotide)) is an enzyme with systematic name poly(deoxyribonucleotide):poly(deoxyribonucleotide) ligase (AMP-forming, NMN-forming). This enzyme catalyses the following chemical reaction

NAD + (deoxyribonucleotide) + (deoxyribonucleotide)$\rightleftharpoons$ AMP + beta-nicotinamide D-ribonucleotide + (deoxyribonucleotide)

Catalyses the formation of a phosphodiester at the site of a single-strand break in duplex DNA.