Probing the interaction of thyroglobulin with metal ions by terbium(III) luminescence spectroscopy.
Mol Cell Endocrinol
; 141(1-2): 21-7, 1998 Jun 25.
Article
em En
| MEDLINE
| ID: mdl-9723881
ABSTRACT
The binding of Ca2+ ions to bovine and human thyroglobulin (Tg) was demonstrated qualitatively by 45Ca overlay on polyvinylidene difluoride (PVDF) membranes. A quantitative analysis of the interaction of metal ions with bovine Tg was conducted by fluorimetric titration of the protein with Tb3+ ions. These have been used with several proteins as isomorphous replacement probes for Ca2+ ions, as protein-bound Tb3+ ions fluoresce, upon irradiation in the UV region, because of energy transfer from tyrosyl and/or tryptophanyl residues. The fluorescence emission spectrum of Tg excited at 280 nm showed, upon addition of Tb3+ ions, a peak at 546 nm and a marked decrease at 335 nm, indicating an efficient Förster energy transfer between bound Tb3+ ions and closely located Tg intrinsic chromophores. Titration of Tg with Tb3+ ions, carried out by monitoring the emitted fluorescence at 546 nm, indicated the presence of 13.15 metal binding sites per Tg molecule.
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Base de dados:
MEDLINE
Assunto principal:
Espectrometria de Fluorescência
/
Térbio
/
Tireoglobulina
/
Cálcio
Idioma:
En
Ano de publicação:
1998
Tipo de documento:
Article