A rationally designed novel receptor for probing cooperative interaction between metal ions and bivalent tryptophan side chain in solution

Abstract

Cooperative interactions between metal ions and bivalent tryptophan side chain are identified in water by fluorescence quenching of a designed novel receptor, EDTA-bis(L-tryptophan methyl ester), supplemented by a circular dichroism study; results revealed that the receptor is capable of distinguishing a variety of metal ions on the basis of their abilities in quenching tryptophan fluorescence and the relative magnitude of these interactions is Cu²⁺ ∼ Fe²⁺ >> Co²⁺ > Ni²⁺ >> Mn²⁺ > Zn²⁺ > La³⁺ > Al³⁺.