adapterligated

Adapter ligation is a molecular biology technique used to attach short synthetic DNA sequences called adapters to the ends of DNA fragments. This process is particularly important in next-generation sequencing (NGS) library preparation. Adapters contain crucial elements such as sequencing primer binding sites, indexing (barcodes) for sample identification, and regions that facilitate amplification or capture of the DNA fragments. The ligation step itself is catalyzed by an enzyme, typically a DNA ligase, which forms phosphodiester bonds to join the adapter and DNA fragment covalently.

The process usually begins with the fragmentation of a DNA sample into smaller pieces. These fragments then have their ends prepared, often by blunting or adding a single-A overhang, depending on the chosen ligation strategy. Next, a solution containing the DNA fragments and a high concentration of adapters is mixed with a DNA ligase enzyme and its required buffer components. The ligase enzyme then efficiently joins the adapters to the ends of the DNA fragments. After the ligation reaction, excess adapters and unligated fragments may be removed through purification steps, such as size selection with beads. The resulting DNA library, now flanked by adapters, is ready for subsequent steps like amplification and sequencing. Adapter ligation is a critical step for enabling diverse applications of NGS, including whole-genome sequencing, exome sequencing, and RNA sequencing.