2-Aminopurine hydrochloride (2-AP) is widely used as a fluorescent analog of adenine in nucleic acid research. Its ability to mimic adenine while exhibiting distinct fluorescence properties makes it valuable for studying DNA and RNA structures, dynamics, and interactions. In molecular biology, it is employed as a probe to investigate base-pairing mechanisms, nucleic acid folding, and enzyme-substrate interactions. Additionally, 2-AP is utilized in mutagenesis studies to understand the impact of base modifications on genetic material. Its fluorescence also aids in real-time monitoring of nucleic acid processes, such as replication and transcription, providing insights into molecular mechanisms at the single-molecule level.