2. Acetoacetate decarboxylase (AADase) is a classic example of an enzyme that significantly changes the pKa of a reactiveside chain by creating a microenvironment that favors one protonation state of this side chain vs the other protonation state.Below is the reaction catalyzed by AADase, which is important for acetone production during biosynthesis of ketone bodiesin mammals and solventogenesis in bacteria:CO2HO"CHз АADaseacetoacetateacetonea) AADase-catalyzed decarboxylation of acetoacetate proceeds through an enzymatic Schiff base. Draw out the mechanismfor this conversion of acetoacetate to acetone, showing enzymatic lysine (Lys, or K) involvement.b) Draw out the protonation/deprotonation equilibrium for Lys. What form of Lys is catalytic in part a: protonated ordeprotonated? If Lys pKa in AADase was the same as its pKa in solution, what would be the predominant form of Lys atphysiological pH? Which way would Lys pKa need to change (if at all) for efficient catalysis? Explain your answer.c) How would the pka for Lys change if it was near a negatively charged residue like Glu? Explain using equilibrium in partb.d) How would the pKa for Lys change if it was near a hydrophobic residue like Val? Explain using equilibrium in part b.

β-oxidation of fatty acid occurs in mitochondria. Before β- oxidation activation of fatty…

Answered: a) AADase-catalyzed decarboxylation of…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter19: The Tricarboxylic Acid Cycle

Section: Chapter Questions

Problem 18P

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a) AADase-catalyzed decarboxylation of acetoacetate proceeds through an enzymatic Schiff base. Draw out the mechanism for this conversion of acetoacetate to acetone, showing enzymatic lysine (Lys, or K) involvement.