Succinyl-CoA synthetase (also called succinate thiokinase) is an enzyme of the citric acid cycle that catalyzes the reaction below:

Succinyl-CoA + Pi + GDP <=> Succinate + GTP + CoASH ( = -2.9 kJ/mol)

Note that the enzyme is named for the reverse reaction. Plants and bacteria form ATP from ADP instead of using GDP/GTP. GTP and ATP can be interconverted in the reaction catalyzed by NDPK:

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