DNaseI

DNase I is an endonuclease enzyme that digests DNA. It cleaves both single-stranded and double-stranded DNA molecules. The enzyme is produced by the pancreas in mammals and is also found in other organisms. DNase I is a calcium-dependent enzyme, meaning it requires calcium ions to function. It is active over a wide pH range, but is most active at a neutral or slightly alkaline pH.

The primary function of DNase I in vivo is thought to be the removal of cellular DNA, particularly during apoptosis or programmed cell death. In the laboratory, DNase I is widely used as a molecular biology reagent. It is commonly employed to degrade contaminating DNA in RNA preparations, which is crucial for downstream applications like reverse transcription and PCR. It is also used in techniques such as DNA footprinting assays to map DNA-protein binding sites.

DNase I exhibits a preference for cleaving phosphodiester bonds adjacent to a pyrimidine nucleotide (cytosine or thymine). However, this preference is not absolute, and it can cleave DNA at other sites as well. The enzyme is typically supplied as a purified protein in a buffer solution. Its activity can be inhibited by various agents, including divalent cations like magnesium ions, which compete with calcium for binding sites on the enzyme. Understanding the properties and applications of DNase I is essential for many molecular biology procedures.