- Deoxyribonuclease I (DNase I) is an endonuclease enzyme that catalyzes the cleavage of DNA by hydrolyzing the phosphodiester bonds between nucleotides. It specifically targets double-stranded and single-stranded DNA, producing oligonucleotides with 5′-phosphate and 3′-hydroxyl termini. DNase I requires divalent metal ions, typically Mg²⁺ or Ca²⁺, for optimal enzymatic activity.
- DNase I is widely found in animal tissues, particularly in the pancreas, and plays a physiological role in the degradation of extracellular DNA during processes such as apoptosis and inflammation. In research and biotechnology, DNase I is extensively used to eliminate contaminating genomic DNA from RNA preparations prior to reverse transcription, ensuring accurate gene expression analysis. It is also employed in footprinting assays to study protein-DNA interactions, where limited digestion reveals protected regions bound by DNA-binding proteins.
- The enzyme’s activity is influenced by ionic strength and the presence of metal cofactors. Under high concentrations of Mg²⁺, DNase I cleaves both strands of DNA independently, generating blunt or nearly blunt ends. In contrast, in the presence of only Ca²⁺, it binds DNA without cleaving it, which is useful for structural studies.
- Commercial DNase I is commonly available in both recombinant and native forms and is often supplied with RNase-free certification for applications involving RNA. Enzyme inactivation can be achieved by chelating agents like EDTA (which remove divalent cations), heat inactivation, or proteinase K digestion.
- In summary, DNase I is a versatile endonuclease essential for a variety of molecular biology applications, including DNA removal, chromatin structure analysis, and protein-DNA interaction mapping, owing to its ability to precisely and efficiently degrade DNA.
