Specificity comes from the ligation junction rather than hybridization alone. Two oligonucleotide probes must bind adjacent positions on a complementary template, placing their ends in the correct geometry. DNA ligase then catalyzes formation of the phosphodiester bond. If alignment is incorrect, joining is not efficiently supported, so the reaction preferentially produces products matching the intended sequence.
At a potential point-mutation site, the probe boundary can be arranged so that correct base pairing is required for ligation. A matching target supports precise end alignment, whereas a mismatched target is less likely to satisfy the ligase’s joining requirement. This makes the method useful for distinguishing selected sequence variants, although it supports detection of some, rather than all, point mutations.
Thermal cycling drives the repeated reaction in complementary phases. Heating separates previously formed products from template-associated structures, while subsequent reaction conditions enable the probes to hybridize again at neighboring positions. Ligase can then join correctly aligned ends in another round. Repetition increases the amount of target-associated ligated material rather than relying on a single joining event.
A basic workflow begins with a complementary nucleic acid template and two oligonucleotide probes designed to bind next to one another. The probes hybridize, and DNA ligase joins their correctly aligned ends. Thermal cycling then separates products and permits additional hybridization and ligation rounds. The resulting increase in joined products provides amplified material for sequence-specific analysis.
Researchers may choose this technique when sequence discrimination is important, particularly for molecular diagnostics, genotyping, or analysis of low-abundance nucleic acids. Its dependence on correct base pairing at the joining site links product formation to a specific target sequence. Consequently, the method can support detection of selected sequence differences while amplifying material that may initially be scarce.
In molecular diagnostics and genotyping, the method connects a biochemical joining event with the identity of a nucleic acid sequence. Correctly adjacent probes can be ligated only when their ends align with the complementary template, allowing selected target sequences or some point mutations to be distinguished. Repeated cycles increase the available ligated material for subsequent analysis of those targets.