What is formed when succinyl-CoA is converted to succinate?

When succinyl-CoA is converted to succinate, the primary product of this reaction is GTP (or ATP). This conversion occurs in the Citric Acid Cycle during a process known as substrate-level phosphorylation. In this reaction, the high-energy thioester bond in succinyl-CoA is broken, releasing energy that is then used to phosphorylate GDP (or ADP) to form GTP (or ATP).

This step is unique because it directly generates a high-energy nucleotide without the involvement of the electron transport chain, highlighting an important mechanism of energy production within the cycle. The formation of GTP or ATP signifies a direct way in which cells can harness energy from biochemical reactions, making this reaction a crucial point in the cycle.