Intrinsic regulation of substrate fluxes and energy conservation in Ca2+-ATPase.
The Ca2+-ATPase of sarcoplasmic reticulum was utilized to demonstrate an intrinsic regulation of enzyme catalysis, whereby the ratio of forward and reverse flow is altered by the binding of Ca2+ and Pi to the enzyme. This is related to displacement of internal equilibria among intermediate enzyme ligand complexes, independent of the overall equilibrium of the ATP in equilibrium ADP + Pi transformation. A very high energy conservation with a velocity of reverse flow approaching that of forward flow, was obtained by increasing the enzyme affinity for Pi in the presence of Me2SO.
de Meis
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Inesi
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004734:Energy Metabolism; D006868:Hydrolysis; D010710:Phosphates / Q000378:metabolism / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology*
D010710:Phosphates; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; D002118:Calcium; D004121:Dimethyl Sulfoxide