Complex sentence: The common function of helicases accounts for the fact that they display a certain degree of amino acid sequence homology; they all possess sequence motifs located in the interior of their primary structure, involved in ATP binding, ATP hydrolysis and translocation along the nucleic acid substrate.
Split into simpler sentences: The common function of helicases accounts for the fact that they display a certain degree of amino acid sequence homology; they all possess common sequence motifs located in the interior of their primary structure. These are thought to be specifically involved in ATP binding, ATP hydrolysis and translocation on the nucleic acid substrate.