Ligase

=Ligase=

In genetic engineering, **ligases** are enzymes which catalyse the formation of phosphodiester bonds between adjacent nucleotides. They are critical in repairing single-stranded breaks in DNA, which is a key component of both DNA replication and site-directed mutagenesis. Because ligases form 3'-5' phosphodiester bonds, they require a free 5' phosphate to work on.