DNA helicase. Has a broad nucleotide specificity, even being able to hydrolyze ethenonucleotides, and is able to couple the hydrolysis to unwinding of DNA substrates. It is a 3'-5' helicase but at high protein concentrations it can also displace a substrate with a 5' tail. Preferred substrate being one with both single and double-stranded regions of DNA. ATP + H2O = ADP + H(+) + phosphate Monomer. Belongs to the helicase family. UvrD subfamily.