Evidence that deprotonation of serine-55 is responsible for the pH-dependence of the parvalbumin Eu3+ 7F0-->5D0 spectrum.
FEBS Lett
; 314(2): 130-4, 1992 Dec 14.
Article
en En
| MEDLINE
| ID: mdl-1333989
The Eu(III)7F0-->5D0 excitation spectra of the parvalbumins are highly pH-dependent. Below pH 6.0, they exhibit a sharp, partially resolved doublet centered near 5,795 A. However, as the pH is raised, the spectrum becomes increasingly dominated by a much broader signal near 5,784 A. This behavior has been traced to the Eu(III) ion bound at the CD site, but the identity of the moiety undergoing deprotonation remains uncertain. Site-specific mutagenesis studies on the parvalbumin-like protein known as oncomodulin now suggest that the species in question is a liganding serine hydroxyl group. Specifically, replacement of serine-55 by aspartate (the residue present at the corresponding position in the EF site) affords a protein that retains two functional lanthanide binding sites, but fails to undergo the pH-dependent spectral alteration. By contrast, replacement of aspartate-59 by glycine (the corresponding EF site residue) fails to abolish the pH-dependent behavior.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Parvalbúminas
/
Espectrofotometría
/
Proteínas de Unión al Calcio
/
Europio
Límite:
Animals
Idioma:
En
Revista:
FEBS Lett
Año:
1992
Tipo del documento:
Article
Pais de publicación:
Reino Unido