An easy and effective demonstration of enzyme stereospecificity and equilibrium thermodynamics

Enzyme stereospecificity and equilibrium thermodynamics can be demonstrated using the coupling of two amino acid derivatives by Thermoase C160. This protease will catalyze peptide bond formation between Z-L-AspOH and L-PheOMe to form the Aspartame precursor Z-L-Asp-L-PheOMe. Reaction completion manifests itself by precipitation of the product. As the product has almost zero solubility, the equilibrium favors condensation and thus a normally hydrolytic enzyme catalyzes the opposite reaction. Neither Z-D-AspOH with L-PheOMe nor Z-L-AspOH with D-PheOMe produces any visible product.