title: An easy and effective demonstration of enzyme stereospecificity and equilibrium thermodynamics.
abstract: 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.
authors.affiliation: Department of Experimental Sciences, Collège Universitaire de Saint-Boniface, Winnipeg, Manitoba, Canada R2H 0H7.
authors.forename: Chelsea
authors.initials: C
authors.lastname: Herdman
authors.forename: Michael
authors.initials: M
authors.lastname: Dickman
mesh_terms: D001218:Aspartame / Q000138:chemical synthesis*; D002384:Catalysis; D020134:Catalytic Domain; D011232:Chemical Precipitation; D003116:Color; D006863:Hydrogen-Ion Concentration; D008666:Metalloendopeptidases / Q000737:chemistry*; D015394:Molecular Structure; D010447:Peptide Hydrolases / Q000737:chemistry*; D012995:Solubility; D012996:Solutions / Q000737:chemistry; D013237:Stereoisomerism; D013379:Substrate Specificity; D013816:Thermodynamics; D013820:Thermolysin / Q000378:metabolism; D013997:Time Factors
chemical_list: D012996:Solutions; D010447:Peptide Hydrolases; D008666:Metalloendopeptidases; C044194:microbial metalloproteinases; D013820:Thermolysin; D001218:Aspartame