The Collaborative International Dictionary
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.
Wiktionary
n. (context enzyme English) Any of a group of enzymes that catalyze the binding of two molecules; synthetase.
Wikipedia
In biochemistry, a ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond, usually with accompanying hydrolysis of a small pendant chemical group on one of the larger molecules or the enzyme catalyzing the linking together of two compounds, e.g., enzymes that catalyze joining of C-O, C-S, C-N, etc. In general, a ligase catalyzes the following reaction:
Ab + C → A–C + bor sometimes
Ab + cD → A–D + b + c + d + e + fwhere the lowercase letters signify the small, dependent groups. Ligase can join two complementary fragments of nucleic acid and repair single stranded breaks that arise in double stranded DNA during replication.
Usage examples of "ligase".
It had held the mixture of restriction nucleases and DNA ligases that was commonly used to insert genes into bacterial plasmids for cloning, either for identification of gene product or use in gengineering.
After several sixteen-hour days, Daniel succeeded in attaching the appropriate fragments with nucleotide ligases to form the genes.
The array of restriction enzymes for cutting, and ligase enzymes for pasting, was big and versatile.