ligating

Ligating is the act of joining two separate entities by binding or fastening them together. In biology, ligation specifically denotes the enzymatic joining of two DNA or RNA fragments by a ligase. In surgery, ligation means tying off a blood vessel, duct, or hollow organ to prevent bleeding or leakage.

In molecular biology, ligation is used to create recombinant DNA molecules by attaching DNA fragments with cohesive or blunt ends. DNA ligases catalyze the formation of phosphodiester bonds between adjacent nucleotides. Common ligases include T4 DNA ligase and E. coli DNA ligase. Some ligases require ATP as a cofactor; others use NAD+. Ligation efficiency depends on compatible ends, DNA concentration, temperature, and buffer conditions. Blunt-end ligation is generally less efficient than cohesive-end ligation. After ligation, molecules are typically introduced into cells or subjected to further assembly steps. Ligases also play roles in RNA ligation in certain contexts, and are essential in workflows such as ligation-based cloning and library preparation; Gibson Assembly relies on a DNA ligase to seal nicks after overlap annealing.

Surgical ligation involves applying sutures or ligating clips to occlude a vessel or duct. It is used to control hemorrhage, during organ resection, or in various vascular procedures. The technique aims to achieve secure occlusion while minimizing tissue injury and preserving nearby structures. Potential complications include bleeding recurrence, tissue necrosis, strictures, or infection.

Etymology traces ligate to Latin ligare, meaning to bind or tie.