Figure 4

Structure modifications of IslA and truncated forms mediated by EDTA and Ca²⁺ ions measured by intrinsic fluorescence (excitation wavelength = 280 nm, emission wavelength = 348 nm) (a) IslA4, 50 μM EDTA and 500 μM Ca²⁺ ions; (b) IslA3, 50 μM EDTA and 500 μM Ca²⁺ ions; (c) IslA2 1000 μM EDTA and 2000 μM Ca²⁺ ions and (d) IslA 5000 μM EDTA and 7000 μM Ca²⁺ ions. EDTA is added after the first fluorescence measurement; time of Ca²⁺ ions addition is indicated by an arrow. For each case, the fluorescence of the heat denaturated protein is shown as a broken line.