Phosphorylation of Ca2+-ATPase by inorganic phosphate in water-organic solvent media: dielectric constant and solvent hydrophobicity contribution.
The effect of organic solvents on the phosphorylation of the Ca2+-dependent ATPase of sarcoplasmic reticulum by inorganic phosphate in the absence of a calcium gradient was investigated. Kinetic analysis of the reaction in water and water-organic solvent media according to a bireactant scheme shows no correlation between changes in kinetic parameters and the dielectric constant of the mixed solvents. The pronounced increase in equilibrium levels of phosphoenzyme in water-solvent mixtures is attributed to changes in the water activity of the medium.
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D010710:Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D012997:Solvents; D014867:Water
D010710:Phosphates; D012997:Solvents; D014867:Water; D000252:Calcium-Transporting ATPases