ligierung

Ligierung (often translated as ligation in English) is a term used to describe the act of joining or tying two structures. In scientific contexts, it most commonly refers to ligation in molecular biology, the process of joining DNA fragments.

In molecular biology, ligation is catalyzed by DNA ligases, enzymes that seal breaks in the sugar-phosphate backbone by forming a phosphodiester bond between adjacent nucleotides. Ligation is essential in cloning and genetic engineering, where a DNA insert is attached to a vector such as a plasmid to create a recombinant molecule that can be propagated in a host organism. Two main end formats matter: cohesive (sticky) ends produced by restriction enzymes that provide complementary overhangs, and blunt ends created by some enzymes or PCR products. Blunt-end ligation is generally less efficient. Ligation reactions rely on ATP-dependent ligases and specific buffers; temperatures vary by ligase, commonly room temperature to 16–37°C, with overnight incubations sometimes used to improve yields.

Besides molecular biology, ligierung also refers to surgical ligation: the tying off of a blood vessel, duct, or other structure using sutures, ligatures, or clips to stop bleeding or occlude flow. In medicine, tubal ligation is a common permanent sterilization procedure.

Historical development notes that DNA ligases were discovered in the mid-20th century, with T4 DNA ligase from bacteriophage T4 becoming a widely used laboratory enzyme due to its robust activity.

Overall, ligierung denotes a class of procedures that connect separate elements, either at the molecular level or in surgical practice, using ligases or ligatures.