@AhmedAfifi I’m not sure if you have this original image on hand or if you know that the new image in this suggestion is from us. If not, could you create another one with succinate labeled on the left & succinyl CoA on the right?
I believe this card is correct as is. In the TCA cycle succinyl CoA is turned into succinate by the enzyme succinyl CoA synthetase. The following image is from Kahn Academy:
The “fixed image” on the suggestion is incorrect. Succinyl CoA is on the left and has the CoA-S attached to the 4C backbone. That is why the name is succinyl-CoA because the CoA is attached. I think some of the confusion here is in the name of the enzyme, succinyl CoA synthetase. This reaction is reversible, but in the TCA cycle does not synthesize succinyl-CoA, but carries out the cleavage of the thioester in succinyl CoA to form succinate. This step is coupled to create a GTP.
This naming convention is similar to how in the last step of glycolysis, PEP to pyruvate, is catalyzed by pyruvate kinase, even though pyruvate kinase is not removing a phosphate like a kinase normally does, but is phosphorylating PEP to make pyruvate. This reaction is also reversible under non-standard condition in a lab, and the researcher who originally isolated pyruvate kinase saw that it was exhibiting kinase activity and named it as such. “The cytosolic enzyme that catalyzes dephosphorylation of phospho-enol pyruvate (PEP) was inappropriately named pyruvate kinase before it was recognized that direct phosphorylation of pyruvate does not occur under physiological conditions, and that this enzyme acts only in the direction of dephosphorylation” Goodman HM (2009). Basic Medical Endocrinology (4th ed.). Elsevier. p. 132.
I remember fixing this card a while back. Perhaps @sabrinanagy1 doesn’t have the updated card?
Below is my accepted suggestion from August.
You’re right. That does look like it’s the case