P. SuntornthiticharoenS. PetmitrP. Chavalitshewinkoon-PetmitrMahidol University2018-08-202018-08-202006-10-01Parasitology. Vol.133, No.4 (2006), 389-39814698161003118202-s2.0-33750214366https://repository.li.mahidol.ac.th/handle/123456789/23299Plasmodium falciparum has developed resistance to most anti-malarials; therefore, an investigation of potential targets should be performed. DNA helicases are enzymes that catalyse the unwinding of double-stranded DNA to provide single-stranded templates for DNA replication, repair and recombination. In this study, a DNA helicase (PfDH A) was purified from a crude extract of Plasmodium falciparum. DNA helicase activity was measured by assaying unwinding activity. The apparent molecular weight of PfDH A as determined by SDS-PAGE was 90 kDa. PfDH A moved unidirectionally in the 3′ -to- 5′ direction along the bound strand and preferred a fork-like substrate structure and could not unwind blunt-ended duplex DNA. Unwinding activity required Mg2+ and could be inhibited by 200 mM NaCl or KCl and was dependent on hydrolysis of ATP or dATP. Anthracyclines, including daunorubicin, nogalamycin, doxorubicin, and aclarubicin, inhibited PfDH A activity with IC50 values of 2, 5, 8 and 9 μM, respectively. Based on the results, PfDH A differs from all known human DNA helicases. However, its function and roles in parasite DNA replication need to be elucidated in the future. © 2006 Cambridge University Press.Mahidol UniversityImmunology and MicrobiologyArticleSCOPUS10.1017/S0031182006000527