Figure 4

Role of the Zn ligands in nucleic acid binding.
(A) Binding curves for wild type hUpZnk and mutants (m1: Cys403Ala/Asn406Ala; m2: His411Ala/Cys416Ala; m3: Asn406Cys) with ssDNA, forkDNA, ssRNA and forkRNA. Each experiment was repeated at least three times. (B) Summary of the site-directed mutants. (C) Binding of the hUpZnK fragment to forkDNA and forkRNA substrates, in the presence of increasing amount of EDTA. The presence of EDTA strongly affects binding to DNA substrates, while does not impair binding to RNA, although it changes the relative intensity of the shifted bands.