Further characterization of helicase activity.

<p><b>A,</b> Nucleotide requirement of helicase activity of PfUDN. Helicase activity of PfUDN in the presence of lane 1, dCTP, lane 2, CTP, lane 3, dGTP, lane 4, GTP, lane 5, dATP, lane 6, ATP, lane 7, dTTP and lane 8, UTP. Lane E is enzyme reaction of PfUDN in the absence of any NTP or dNTP. C1 and C2 are reactions without enzyme and B1 and B2 are heat denatured substrates respectively. <b>B,</b> The quantitative enzyme activity data from the autoradiogram in A are shown and the various NTPs/dNTPs used are also written. <b>C,</b> Helicase activity of PfUDN using varying concentration of ATP. Lane 1, 0.5, lane 2, 1.0, lane 3, 1.5, lane 4, 2.0, lane 5, 2.5 and lane 6, 5.0 mM ATP. C1 and C2 are reactions without enzyme and B is heat denatured substrate respectively. Lane E is enzyme reaction in the absence of ATP. <b>D,</b> The quantitative enzyme activity data from the autoradiogram in C are shown and the concentration of ATP used is also written. <b>E,</b> Unwinding activity of PfUDN with blunt end duplex substrate. The helicase reaction was performed under standard assay conditions; the structure of the substrate used and the autoradiogram of the gel are shown. Asterisk (*) denotes the ³²P-labeled end. Lanes 1–6 are the reactions with increasing concentration of enzyme, C is no enzyme control and B is heat-denatured substrate, respectively. <b>F,</b> The quantitative enzyme activity data from the autoradiogram in E are shown and the concentration of PfUDN used is also written.