**Glycolytic aldolase**: retro-aldol of fructose-1,6-bisphosphate → DHAP + G3P (step 4 of glycolysis). - **Citrate synthase**: aldol condensation of acetyl-CoA enolate + oxaloacetate → citrate (step 1 of TCA cycle). - **Fatty acid synthase**: iterative decarboxylative Claisen for chain extension (Ch