Carbonic anhydrase-mimetic bolaamphiphile self-assembly for CO2 hydration and sequestration.

Abstract

A biomimetic catalyst was prepared through the self-assembly of a bolaamphiphilic molecule with histidine moieties for the sequestration of carbon dioxide. The histidyl bolaamphiphilic molecule bis(N-α-amidohistidine)-1,7-heptane dicarboxylate has been synthesized and self-assembled to produce analogues of the active sites of carbonic anhydrase (CA) after association with Zn(2+) ions. Spectroscopic analysis demonstrated the coordination of the Zn(2+) ions with histidine imidazole moieties, which is the core conformation of CA active sites. The Zn-associated self-assembly worked as a CA-mimetic catalyst that shows catalytic activity for CO2 hydration. Evaluation of the kinetics of using para-nitrophenylacetate revealed that the kinetic parameters of the CA-mimetic catalyst were maximized at the optimal Zn concentration and that excess Zn ions resulted in deteriorated catalytic activity. The performance of the CA-mimetic catalyst was enhanced by changing the pH value and temperature of the reaction, which implies that the hydrolysis of the substrate is the rate-determining step. The catalyst-assisted sequestration of CO2 was demonstrated by CaCO3 precipitation upon the addition of Ca(2+) ions. This study offers an easy way to prepare enzyme analogues for CO2 sequestration through the self-assembly of bolaamphiphile molecules with designer biochemical moieties.