helicaseATPase

Helicase ATPase refers to the ATPase activity that powers helicase enzymes, molecular motors that unwind double‑stranded nucleic acids. This activity converts chemical energy from ATP hydrolysis into mechanical work that separates strands and enables translocation along nucleic acids.

Most DNA helicases belong to the SF1 and SF2 superfamilies and are P-loop ATPases characterized by conserved Walker A and B motifs, sensor residues, and coupling elements. Binding of ATP induces conformational changes that promote nucleic acid binding and translocation; hydrolysis to ADP and inorganic phosphate triggers a reset that advances the enzyme along the substrate, often with a defined polarity (5′→3′ or 3′→5′).

Architecturally, helicases vary: some are monomeric or dimeric, while many essential in replication form hexameric rings that encircle one strand of DNA and move in a stepwise fashion via sequential ATP hydrolysis. Other helicases translocate along RNA or DNA for roles in transcription, processing, and repair. Structural domains outside the motor core often provide nucleic acid specificity and interactions with partner proteins.

Biological roles of helicase ATPase activity are broad, including DNA replication, repair, recombination, transcription, and RNA metabolism. In cells, helicases collaborate with clamp loaders, polymerases, and repair factors, and their activity is tightly regulated to maintain genome integrity and proper gene expression. Biochemically, ATPase activity is typically stimulated by nucleic acids; its kinetics (for example, kcat and Km for ATP) are commonly used to characterize helicase function and mechanism in vitro.