pH and magnesium dependence of ATP binding to sarcoplasmic reticulum ATPase. Evidence that the catalytic ATP-binding site consists of two domains.
نویسندگان
چکیده
منابع مشابه
pH and magnesium dependence of ATP binding to sarcoplasmic reticulum ATPase. Evidence that the catalytic ATP-binding site consists of two domains.
Nucleotide binding to sarcoplasmic reticulum vesicles was investigated in the absence of calcium using both filtration and fluorescence measurements. Filtration assays of binding of radioactive nucleotides at concentrations up to 0.1 mM gave a stoichiometry of one ATP-binding site/sarcoplasmic reticulum ATPase molecule. When measured in the presence of calcium under otherwise similar conditions...
متن کاملDependence on membrane lipids of the effect of vanadate on calcium and ATP binding to sarcoplasmic reticulum ATPase.
The affinity of the sarcoplasmic reticulum transport ATPase for calcium and ATP is not affected by lipid deprivation while vanadate binding is completely abolished. Lipid substitution restores vanadate binding as well as the vanadate induced disappearance of the enzyme's high affinity calcium and nucleotide binding sites. Nucleotide binding is simultaneously restored with the displacement of va...
متن کاملBinding to Sarcoplasmic Reticulum ATPase Revisited
H+ and Mga+ are known to inhibit Ca2+ binding to the transport sites of sarcoplasmic reticulum-ATPase. Evaluation of the affinity for the Ca2+ binding sites requires measurement of the amount of Ca2+ bound to ATPase as a function of the free Ca" concentration imposed by a Ca2+ chelator. The choice of the chelator is crucial as it determines the accuracy of the free Ca2+ concentration. At pH > ...
متن کاملProtonation of the sarcoplasmic reticulum Ca-ATPase during ATP hydrolysis.
pH changes of the reaction medium (pH 6.35) following addition of MgATP were determined at 4 degrees C with sarcoplasmic reticulum vesicles in the presence of 0.1 mM CaCl2 and 5 mM MgCl2. With intact vesicles, a pronounced acidification following a slight alkalinization was induced by MgATP, indicating H+ ejection from vesicles. This agrees with previous observations by several investigators th...
متن کاملA conformational change of N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine-labeled sarcoplasmic reticulum Ca2+-ATPase upon ATP binding to the catalytic site.
Sarcoplasmic reticulum vesicles were modified with a fluorescent thiol reagent, N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine. One mol of readily reactive thiols per mol of the Ca2+-ATPase was labeled without a loss of the catalytic activity. The fluorescence of the label increased by 8% upon binding of Ca2+ to the high affinity sites of the enzyme. This fluorescence enhancement probably ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Journal of Biological Chemistry
سال: 1990
ISSN: 0021-9258
DOI: 10.1016/s0021-9258(19)40236-6