Question

The ΔG’o for the hydrolysis of phosphoarginine to arginine and Pi is – 32 kJ/mol. What is the actual free-energy change (ΔG) for the reaction at 25oC and pH 7.0 in resting lobster muscle where the concentrations of phosphoarginine, arginine, and Pi are: 6.8 mM, 2.6 mM, and 5 mM respectively.

Answer 1

K for the reaction at 25^o C & pH 7 in resting lobster muscle = [ ( 5 x 10 ^-3 ) ( 2.6 x 10^-3 )] / 6.8 x 10^-3

---------------------------------------------------------------------------------------- = 1.91176 x 10^-3

G = - 2.303 x 8.3145 x 298 log ( 1.91176 x 10^-3 )

------ = - 5706 .1915 x (- 2.7185 )

------- = 15.5126 KJ / mol

or,----- = 15.51 KJ / mol

So , actual G in resting lobster muscle at 25^o C & pH 7 = -32 - [ ( 15.51 ) ]

----------------------------------------------------------------------------------------- = - 47.51 KJ /mol   

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