Nucleotide-binding sites in the functional unit of sarcoplasmic reticulum Ca2+-ATPase as studied by photoaffinity spin-labeled 2-N3-SL-ATP.
Biol Chem
; 382(3): 417-23, 2001 Mar.
Article
em En
| MEDLINE
| ID: mdl-11347889
ABSTRACT
2-N3-SL-ATP [2-azido-2',3'-O-(1-oxyl-2,2,5,5-tetramethyl-3-carbonyl-pyrroline) adenosine triphosphate], a photoaffinity spin-labeled derivative of ATP with a nitroxide moiety attached to the ribose ring and an azido group attached to C2 of the adenine ring, was used to study the nucleotide-binding site stoichiometry of sarcoplasmic reticulum (SR) Ca2+-ATPase. The label was shown to bind at the catalytic site of the enzyme, even though the rate of hydrolysis was poor. A maximal binding ratio of 1 mol/mol of ATPase was found. The ESR spectra showed signals from spin-spin interactions between two radicals corresponding to a distance of about 15 A between labels bound to adjacent sites on the enzyme. This indicates that the minimal functional unit of the Ca2+-ATPase is a dimer with the nucleotide-binding sites in close proximity.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Retículo Sarcoplasmático
/
Azidas
/
Trifosfato de Adenosina
/
ATPases Transportadoras de Cálcio
/
Nucleotídeos
Limite:
Animals
Idioma:
En
Revista:
Biol Chem
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Alemanha