Static and Kinetic Studies of the Interaction of Tryptophan with Fluorescein Mercury(II) Acetate by Fluorescence and Absorption Spectrophotometry and by Fluorescence Stopped-fiow Method

Abstract
Fluorescein mercury(II) acetate (FMA) was found to combine with tryptophan (Trp) to form the FMA–Trp complex. The interaction was interpreted in terms of a reversible single-step binding mechanism. The dissociation constant of the complex estimated kinetically by means of the stopped-flow method using the forward and backward rate constants was in good agreement with that obtained by the static method. From comparison with several derivatives of tryptophan, it was found that the protonated amino group and the indole moiety of tryptophan are essential for the complex formation.