exonukleázos

Exonukleázos are enzymes that break down nucleic acids by cleaving nucleotides from the ends of a polynucleotide chain. This is in contrast to endonukleázos, which cleave phosphodiester bonds within the nucleic acid chain. Exonukleázos can act on either DNA or RNA and are essential for various biological processes.

There are two main types of exonukleázos based on their direction of activity: 5' to 3' exonukleázos and 3' to 5' exonukleázos. A 5' to 3' exonukleázos removes nucleotides starting from the 5' end of the strand, while a 3' to 5' exonukleázos removes them from the 3' end. Some exonukleázos are specific for single-stranded nucleic acids, while others can act on double-stranded molecules.

In living organisms, exonukleázos play critical roles in DNA repair, recombination, and degradation. For instance, during DNA repair, exonukleázos are involved in removing damaged nucleotides before new ones are synthesized. They are also involved in the processing of RNA molecules, such as the removal of primer sequences during DNA replication. In bacteria, specific exonukleázos are part of the restriction-modification system, which protects the cell from foreign DNA. The activity of exonukleázos is tightly regulated to ensure proper cellular function and prevent uncontrolled nucleic acid degradation.