Endonuclease PacI is primarily used in molecular biology for DNA manipulation. Its specific application is in the precise cutting of DNA at particular recognition sites, which is crucial for cloning and genetic engineering experiments. Researchers utilize this enzyme to create compatible ends for DNA fragments, facilitating the insertion of genes into plasmids or other vectors. This process is essential for constructing recombinant DNA molecules, which are fundamental in studying gene function, producing proteins, and developing genetically modified organisms. Additionally, PacI is employed in genome editing and sequencing projects, where accurate DNA cleavage is required to analyze or modify genetic material. Its role in these applications makes it a valuable tool in biotechnology and genetic research.