Figure 3

Circular dichroism spectra of Tat Eli in the presence of Zn²⁺. CD spectra of Tat Eli were measured from 260 to 178 nm at 20°C with increasing molar equivalents of Zn²⁺ (0, 1, 2, 3, 4, 8 and 16) in 20 mM phosphate buffer pH 4.5 (panel A) and pH 7 (panel B). A full precipitation occurs with a Zn²⁺ ratio 1:16 at pH 4.5 (A) while a precipitation starts with a ratio 1:8 at pH 7 (B). The binding of Zn²⁺ does not modify the structure of Tat Eli for the ratio 1:1, 1:2, 1:3 and 1:4.