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. Author manuscript; available in PMC: 2014 Mar 26.
Published in final edited form as: Biochemistry. 2013 Feb 4;52(12):10.1021/bi301491r. doi: 10.1021/bi301491r

Figure 3.

Figure 3

Free energy profiles for the SCOT-catalyzed transfer of CoA from SucCoA to form the E-CoA covalent intermediate (through transition state (‡)CoA), and for the transfer of a hypothetical thiol from SucSR to give E-SR, for which the binding interactions with only the pantoic acid domain have been eliminated (through transition state (‡)SR). The binding interactions between SCOT and the pantoic acid domain stabilize the transition state for transfer of CoA to SCOT by 5 kcal/mol but destabilize the resulting E-CoA intermediate by 5 kcal/mol. The net effect is a 10 kcal/mol smaller barrier for the reverse transfer to succinate of CoA from E-CoA than for the transfer of SR from E-SR.