DNA polymerase activity was detected and characterized in nuclear extracts from trophozoites of Entamoeba histolytica. The activity was high at pH 2 to pH 6, but at pH 8 and 10 the activity was very low. The presence of K+ was inhibitory for the activity and a higher concentration of K+ markedly inhibited the activity. Magnesium ions (Mg2+) were absolutely required for activity and its optimal concentration was 6 to 8 mM. The activity was markedly inhibited by aphidicolin which is an inhibitor of mammalian DNA polymerases α, δ, and ε and also by N-ethylmaleimide which is an inhibitor of DNA polymerases, α, γ, δ and ε. However, inhibition of the activity by 2',3'-dideoxythymidine-5'-triphosphate which is an inhibitor of DNA polymerases β and γ was relatively weak. Thus sensitivity of the E. histolytica enzyme to these inhibitors was similar to that of mammalian DNA polymerases (α, δ and ε) of the α family. Monoclonal antibodies against human DNA polymerase α did not bind to DNA polymerase of E. histolytica.
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