Does CoA always bind to organic molecules through a thiol bond? Sometimes I see it written as SCoA in textbooks but sometimes it's just written as CoA, are those actually chemically different, or just laziness on the part of the author?


1 Answer 1


This is coenzyme A (CoA). As you can see, it has an -SH group at its end. So when it interacts with other reagents, it forms thiolesters. CoA is just shorter.

Coenzyme A

  • 2
    $\begingroup$ Your answer is correct. However, I would mention a third alternative that the questioner may encounter — the one I prefer myself. This is not to use SCoA, but HSCoA in equations. That way e.g. acetylCoA can be written as CH3CO-SCoA and the chemistry of the reaction is apparent. $\endgroup$
    – David
    Commented May 6, 2016 at 22:40
  • $\begingroup$ @David CoA-S-Ac is a term for acetyl CoA, that I have commonly encountered. $\endgroup$
    Commented May 7, 2016 at 4:16
  • $\begingroup$ @WYSIWYG Fashions change. I distinctly remember writing CoASH, in fact, but that was many years ago. There may well be a rationale for the change/variation. Anyway readers may encounter different abbreviations for the same thing. $\endgroup$
    – David
    Commented May 7, 2016 at 7:15
  • $\begingroup$ Okay, thanks for these hints. This may will diminish understanding issues. $\endgroup$
    – SeRe
    Commented May 7, 2016 at 10:36

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