nucleasen

Nucleases are enzymes that catalyze the cleavage of nucleic acids, including DNA and RNA. They are broadly classified as endonucleases, which cut within a nucleic acid strand, and exonucleases, which remove nucleotides from the ends. Based on substrate specificity, nucleases are divided into DNases, RNases, and, in many cases, into sequence-specific restriction endonucleases and non-specific nucleases.

Most nucleases require divalent metal ions, typically Mg2+ or Mn2+, for activity. Some RNases are exceptionally robust and can function under harsh conditions, which makes RNase-free handling essential in laboratories.

Endonucleases include restriction enzymes that recognize specific DNA sequences and cut within those sites, producing defined fragments, as well as non-specific endonucleases such as DNase I. Exonucleases act from the ends of DNA or RNA, trimming nucleotides successively. Examples include DNase I, RNase A, and various restriction enzymes.

In biology, nucleases participate in DNA replication, repair, recombination, RNA processing and turnover, and protective defense systems in bacteria (restriction-modification). They also play roles in programmed cell death in some organisms.

In biotechnology and research, nucleases are tools for manipulating nucleic acids. They are used to remove DNA from RNA samples, to map or generate ends, to create small fragments for cloning, and as components of gene-editing systems such as CRISPR-associated nucleases. Handling requires care to prevent unwanted degradation, especially of RNA, and RNase-free environments are standard.