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. Author manuscript; available in PMC: 2013 Feb 28.
Published in final edited form as: Biochemistry. 2012 Feb 16;51(8):1658–1668. doi: 10.1021/bi201899b

Scheme 1.

Scheme 1

Catalytic mechanism of E. coli KDPG aldolase.(29, 30) The substrate is bound as a Schiff base adduct with Lys133 (I) and water W1 arises from the keto-group that is displaced by Schiff base formation.(30) Glu45 catalyzes proton removal from the C4 hydroxyl of KDPG. This proton transfer is mediated by W1. The C3-C4 bond is broken with the Schiff base stabilizing the formation of a carbanion at C4 to form D-glyceraldehyde-3-phosphate and a pyruvyl-enamine (II). The pyruvyl-enamine is protonated by the acidic form of Glu-45 via W1 to form a Schiff base (III). Finally, the pyruvyl-Schiff base is hydrolyzed resulting in the free enzyme (IV).