helicase

Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied. During DNA replication, DNA helicases unwind DNA at positions called origins where synthesis will be initiated. DNA helicase continues to unwind the DNA forming a structure called the replication fork, which is named for the forked appearance of the two strands of DNA as they are unzipped apart. The process of breaking the hydrogen bonds between the nucleotide base pairs in double-stranded DNA requires energy. To break the bonds, helicases use the energy stored in a molecule called ATP, which serves as the energy currency of cells. DNA helicases also function in other cellular processes where double-stranded DNA must be separated, including DNA repair and transcription. RNA helicases are involved in shaping the form of RNA molecules, during all processes involving RNA, such as transcription, splicing, and translation.