Stabilisation of Na,K-ATPase structure by the cardiotonic steroid ouabain.
Biochem Biophys Res Commun
; 435(2): 300-5, 2013 May 31.
Article
em En
| MEDLINE
| ID: mdl-23618866
ABSTRACT
Cardiotonic steroids such as ouabain bind with high affinity to the membrane-bound cation-transporting P-type Na,K-ATPase, leading to complete inhibition of the enzyme. Using synchrotron radiation circular dichroism spectroscopy we show that the enzyme-ouabain complex is less susceptible to thermal denaturation (unfolding) than the ouabain-free enzyme, and this protection is observed with Na,K-ATPase purified from pig kidney as well as from shark rectal glands. It is also shown that detergent-solubilised preparations of Na,K-ATPase are stabilised by ouabain, which could account for the successful crystallisation of Na,K-ATPase in the ouabain-bound form. The secondary structure is not significantly affected by the binding of ouabain. Ouabain appears however, to induce a reorganization of the tertiary structure towards a more compact protein structure which is less prone to unfolding; recent crystal structures of the two enzymes are consistent with this interpretation. These circular dichroism spectroscopic studies in solution therefore provide complementary information to that provided by crystallography.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ouabaína
/
Membrana Celular
/
ATPase Trocadora de Sódio-Potássio
Idioma:
En
Revista:
Biochem Biophys Res Commun
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Reino Unido