deoxyribonuclease

Deoxyribonuclease, or DNase, refers to enzymes that hydrolyze phosphodiester bonds in DNA, producing shorter DNA fragments or nucleotides. DNases are found across organisms, including bacteria, fungi, plants, and animals, and they participate in DNA turnover, apoptosis, immune defense, and tissue remodeling. They differ in metal ion requirements, pH optima, substrate preference, and cellular localization.

DNase I is the most studied mammalian DNase. It is a non-specific endonuclease that cleaves both single- and double-stranded DNA in the presence of divalent cations such as Mg2+ and Ca2+. It can function extracellularly and intracellularly and is encoded by the DNASE1 gene in humans. It is inhibited by actin. Recombinant human DNase I, sold as dornase alfa, is used clinically to reduce mucus viscosity in cystic fibrosis. In laboratories, DNase I is widely used to remove DNA contamination from RNA samples and to decrease viscosity of biological preparations.

DNase II is an acid DNase operating in lysosomes and endosomes, functioning under acidic conditions and without the need for divalent metal ions. It participates in degradation of DNA from engulfed material and in the clearance of cellular DNA during apoptosis, contributing to intracellular recycling and immune regulation.

Additional DNases, such as DNASE1L3, contribute to extracellular DNA turnover and have roles in immune tolerance. Defects or imbalances in DNase activity can be associated with autoimmune conditions where extracellular DNA persists.

Overall, DNases are essential enzymes in molecular biology, medicine, and physiology, with roles shaped by their family, localization, and biochemical requirements. Handling of DNases requires careful DNase-free conditions to prevent unwanted DNA degradation.