Entry M0236 18.104.22.168 3-dehydro-L-gulonate-6-phosphate decarboxylase
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The carbonyl of the intermediate reforms and the C1 position is protonated. This can occur at the si-face (involving the si-water and His136, shown here) or at the re-face (involving the re-water and Arg139).
Comment: The enediolate can be protonated from either the re- or si-face. The si-face water is protonated by His136 to allow it to act as a proton shuttle. However, if the protonation occurs at the re-face, Arg139A has been proposed to be the proton source. Since protonation at the si-face is favoured in a roughly 2:1 ratio, this is the mechanism that has been shown.
Amino acids involved in the reaction step.
Metal Cofactors involved in Step 02
||Bonds Changed in Order
||Atom Types Involved
The C-O bond changes from a single to double bond
The C-C bond changes from a double to single bond
View similar reactions in MACiE.