Fluorescent labeling of (Na+ + K+)-ATPase by 5-iodoacetamidofluorescein.
5-Iodoacetamidofluorescein (5-IAF) covalently labels dog kidney (Na+ + K+)-ATPase with approximately 2 moles incorporated per mole of enzyme. ATPase and K+-phosphatase activities are fully retained after reaction, and the kinetic parameters for Na+, K+, Mg2+, ATP and p-nitrophenyl phosphate are likewise not significantly affected. The fluorescence of the bound 5-IAF is increased by ATP, Na+, and Mg2+, and decreased by K+. These fluorescence changes likely reflect ligand-induced stabilization of the E1 or E2 states of the enzyme.
D000818:Animals; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D005452:Fluoresceins / Q000494:pharmacology*; D007679:Kidney Medulla / Q000201:enzymology; D007700:Kinetics; D008970:Molecular Weight; D011485:Protein Binding; D000254:Sodium-Potassium-Exchanging ATPase / Q000302:isolation & purification / Q000378:metabolism*
D005452:Fluoresceins; C015296:5-iodoacetamidofluorescein; D000254:Sodium-Potassium-Exchanging ATPase