text: The concentration of ATP must be kept above equilibrium level so that the rates of ATP-dependent biochemical reactions meet metabolic demands. A decrease in ATP will result in a decreased saturation of enzymes that use ATP as substrate, and thus a decreased reaction rate. The concentration of ATP is also kept higher than that of AMP,  and a decrease in the ATP/AMP ratio triggers AMPK to activate cellular processes that will return ATP and AMP concentrations to steady state.
  In one step of the glycolysis pathway catalyzed by PFK-1, the equilibrium constant of reaction is approximately 1000, but the steady state concentration of products (fructose-1,6-bisphosphate and ADP) over reactants (fructose-6-phosphate and ATP) is only 0.1, indicating that the ratio of ATP to AMP remains in a steady state significantly above equilibrium concentration.  Regulation of PFK-1 maintains ATP levels above equilibrium.
  In the cytoplasm of hepatocytes, the steady state ratio of NADP to NADPH is approximately 0.1 while that of NAD to NADH is approximately 1000, favoring NADPH as the main reducing agent and NAD as the main oxidizing agent in chemical reactions.