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Terbium(III) as fluorescence probe in the study of the interaction of rare earth and transition metal ions with concanavalin A
Author(s) -
Yang Pin,
Ma GuiBin,
Yang BinSheng
Publication year - 1989
Publication title -
acta chimica sinica english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 0256-7660
DOI - 10.1002/cjoc.19890070510
Subject(s) - terbium , chemistry , fluorescence , ionic radius , europium , metal ions in aqueous solution , lanthanide , titration , inorganic chemistry , dissociation constant , ion , photochemistry , metal , organic chemistry , biochemistry , physics , receptor , quantum mechanics
The binding site for calcium (II) on concanavalin A (con‐A) can be occupied by rare earth ions. When terbium (III) ion binds to con‐A, its fluorescence intensity is tremendously enhanced because of an energy transfer from one or more tryptophan residues in close proximity to the bound terbium (III). The dissociation constant of the con‐A‐Tb (III) complex is 8.90 × 10 −6 M, obtained from terbium (III) fluorescence titration with con‐A. The dissociation constant of the complexes of con‐A with other rare earth and transition metal ions was obtained through their competition with terbium (III) in the reaction with con‐A, i. e. the quenching of con‐A enhanced fluorescence. The results indicate that the binding of rare earth ions with con‐A is dependent not only on their ionic radius but also on the hard‐soft acid‐base strength of the metal ions.