Khan Passage: Basic concepts in bioenergetics: phosphoryl group transfers and ATP hydrolysis

[lightng]

Does anyone understand the logic of the answer pertaining to the last question of this Khan Academy passage?

https://www.khanacademy.org/test-pr...phosphoryl-group-transfers-and-atp-hydrolysis

I'm not quite sure why the answer isn't just -34 Kj/mol.

Why is it "more than -34 Kj/mol" but less than 0 kj/mol?

They administered a pyrophosphatase inhibitor but that shouldn't have an effect on the thermodynamics of the reaction

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[theonlytycrane]

The -34 kJ / mol is from the adenylyl transfer and assumed PPi cleavage. The PPi inhibitor blocks the PPi cleavage so the energy release would not be the full -34 kJ / mol.

 

[lightng]

Oh wow. Don't know how my brain got tangled on such a simple concept! Thanks so much