Figure 2. Tryptophan (A) and ANS (B) fluorescence.

(A) Tryptophan fluorescence spectra were recorded for a sample containing 5 μM secretagogin, 1 mM DTT, 0.5 mM EGTA, 0.15 M KCl and 2 mM Tris/HCl (pH 7.5) (dotted line), after which MgCl₂ (pH 7.5) was added to a concentration of 5 mM (broken line). Then, 1 mM CaCl₂ (pH 7.5) was added to the same solution (continuous line). (B) ANS fluorescence spectra were recorded for a sample containing 120 μM ANS, 5 μM secretagogin, 1 mM DTT, 0.5 mM EGTA, 0.15 M KCl and 2 mM Tris/HCl (pH 7.5) (dotted line). MgCl₂ (pH 7.5) was then added to a concentration of 5 mM (broken line). Finally, 1 mM CaCl₂ (pH 7.5) was added to the same solution (continuous line).