Confining the sodium pump in a phosphoenzyme form: the effect of lead(II) ions.
Biophys J
; 99(7): 2087-96, 2010 Oct 06.
Article
em En
| MEDLINE
| ID: mdl-20923642
ABSTRACT
The effect of Pb(2+) ions on the Na(+),K(+)-ATPase was investigated in detail by means of steady-state fluorescence spectroscopy. Experiments were performed by using the electrochromic styryl dye RH421. It is shown that Pb(2+) ions can bind reversibly to the protein and do not affect the Na(+) and K(+) binding affinities in the E(1) and P-E(2) conformations of the enzyme. The pH titrations indicate that lead(II) favors binding of one H(+) to the P-E(2) conformation in the absence of K(+). A model scheme is proposed that accounts for the experimental results obtained for backdoor phosphorylation of the enzyme in the presence of Pb(2+) ions. Taken together, our results clearly indicate that Pb(2+) bound to the enzyme stabilizes an E(2)-type conformation. In particular, under conditions that promote enzyme phosphorylation, Pb(2+) ions are able to confine the Na(+),K(+)-ATPase into a phosphorylated E(2) state.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfoproteínas
/
ATPase Trocadora de Sódio-Potássio
/
Chumbo
Limite:
Animals
Idioma:
En
Revista:
Biophys J
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Itália