# Maximum ratio of calcium, atp hydrolysis

1. Feb 3, 2016

### lilphy

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Hello,
1-The standard free energy associated to the hydrolysis of one ATP mole is -31 kJ. What would be the energy when [ATP]=5mM , [ADP]=0.5mM and [Pi]=1mM
2-Calculate the free energy required to move 1 mol of Ca2+ ions from the outside of the cell (where [Ca2+] = 10-3) to the inside (where [Ca2+] = 10-7) when the membrane potential is -70mV and the temperature is 25°C
3- What would be the maximum ratio of [Ca2+]out/[Ca2+]in that the atp hydrolysis would fight using the ATP ADP and PI concentrations and potential given above.

1/ I just used the formula
dG=dGo + RT ln ( [ADP][PI]/[ATP] )
I found dG=-53.8 kJ

2/ dG=RTln([Ca2+]o/[Ca2+]in) - 2*F*V
dG=36.3 kJ

3/ I calculated the equilibrium constants for each reaction, multiplied them to get [Ca2+]out[ADP][Pi] / [Ca2+]in[ATP] and then found the ratio from that is that correct ?
Thanks

Last edited: Feb 3, 2016
2. Feb 8, 2016