The sarcoplasmic reticulum Ca2+-ATPase, pumps 2 mol Ca2+ out of sarcomeres per mol ATP hydrolyzed. Part A: Given the following steady-state concentrations and a membrane potential of 64 mV (inside negative), calculate ΔG for the following active transport process at 37 ∘C and pH=7.4: 2Ca2+(in)+ATP+H2O→2Ca2+(out)+ADP+Pi+H+ ATP=2.8mM,ADP=206μM,Pi=5.4mM,Ca2+(in)=34μM,Ca2+(out)=2.2mM The answer to part A was -7.4 kJ/mol I need help with Part B: Part B: The activity of the Ca2+-ATPase is regulated reversibly under normal conditions to maintain homeostatic concentrations of Ca2+ inside the sarcomere. However, in a rare genetic disorder, irreversible activation of the Ca2+-ATPase can occur. Assuming 37 ∘C, pH=7.4, and the steady-state concentrations for ATP, ADP Pi, and Ca2+(out) given in part (a) calculate the minimum [Ca2+] inside a sarcomere that has irreversibly activated Ca2+-ATPase (i.e., the Ca2+-ATPase activity is always “on”).
The sarcoplasmic reticulum Ca2+-ATPase, pumps 2 mol Ca2+ out of sarcomeres per mol ATP hydrolyzed. Part A: Given the following steady-state concentrations and a membrane potential of 64 mV (inside negative), calculate ΔG for the following active transport process at 37 ∘C and pH=7.4: 2Ca2+(in)+ATP+H2O→2Ca2+(out)+ADP+Pi+H+ ATP=2.8mM,ADP=206μM,Pi=5.4mM,Ca2+(in)=34μM,Ca2+(out)=2.2mM
The answer to part A was -7.4 kJ/mol
I need help with Part B:
Part B:
The activity of the Ca2+-ATPase is regulated reversibly under normal conditions to maintain homeostatic concentrations of Ca2+ inside the sarcomere. However, in a rare genetic disorder, irreversible activation of the Ca2+-ATPase can occur. Assuming 37 ∘C, pH=7.4, and the steady-state concentrations for ATP, ADP Pi, and Ca2+(out) given in part (a) calculate the minimum [Ca2+] inside a sarcomere that has irreversibly activated Ca2+-ATPase (i.e., the Ca2+-ATPase activity is always “on”).
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