Substrate dependence and a catalytic efficiency of a metalloenzyme mimic

A dinuclear macrocyclic amine ligand with a proximal cyclodextrin ring was synthesized for demonstrating cooperative hydrolysis of an activated ester mimicking the active site or carboxypeptidase A. The macrocyclic polyamine presented a tetrahedral coordination site for the catalytic Zn(II) ions whereas a proximal ß-cyclodextrin moiety afforded binding site for alkaline earth metal ions through the hydroxyl groups around the cyclodextrin ring. This presentation will focus on the kinetics of the hydrolysis of an activated ester at the pH corresponding to the pKa of the Zin(II) bound water that upon detonation serves as a nucleophile during the hydrolysis. Rate enhancement for the hydrolysis of p-nitrophenyl phosphate (PNPA) with the Zn(II) complex in presence of Ba(II) ion bound to ß-cyclodextrin over that of the complex in its absence will be presented. The Lewis acid activation of the activated ester substrate by the ß-cyclodextrin-bound Ba(II) ions will be discussed. The effect of substrate concentration on the catalytic reaction will be examined to determine the catalytic turnover number.
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Abstract/Description: A dinuclear macrocyclic amine ligand with a proximal cyclodextrin ring was synthesized for demonstrating cooperative hydrolysis of an activated ester mimicking the active site or carboxypeptidase A. The macrocyclic polyamine presented a tetrahedral coordination site for the catalytic Zn(II) ions whereas a proximal ß-cyclodextrin moiety afforded binding site for alkaline earth metal ions through the hydroxyl groups around the cyclodextrin ring. This presentation will focus on the kinetics of the hydrolysis of an activated ester at the pH corresponding to the pKa of the Zin(II) bound water that upon detonation serves as a nucleophile during the hydrolysis. Rate enhancement for the hydrolysis of p-nitrophenyl phosphate (PNPA) with the Zn(II) complex in presence of Ba(II) ion bound to ß-cyclodextrin over that of the complex in its absence will be presented. The Lewis acid activation of the activated ester substrate by the ß-cyclodextrin-bound Ba(II) ions will be discussed. The effect of substrate concentration on the catalytic reaction will be examined to determine the catalytic turnover number.
Subject(s): Undergraduate Research
Metalloenzyme mimic
Catalytic hydrolysis