Accelerated CO₂ Hydration with Thermostable Sulfurihydrogenibium azorense Carbonic Anhydrase-Chitin Binding Domain Fusion Protein Immobilised on Chitin Support.

Juan Hou,Michal Kaczmarek,Yuanmei Liang,Pengyu Chen,Peng Jin,Maurycy Daroch,Xingkang Li,Kai Li

doi:10.3390/ijms20061494

Juan Hou, Michal Kaczmarek + Show 6 more

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https://doi.org/10.3390/ijms20061494

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Abstract

Carbonic anhydrases (CAs) represent a group of enzymes that catalyse important reactions of carbon dioxide hydration and dehydration, a reaction crucial to many biological processes and environmental biotechnology. In this study we successfully constructed a thermostable fusion enzyme composed of the Sulfurihydrogenibium azorense carbonic anhydrase (Saz_CA), the fastest CA discovered to date, and the chitin binding domain (ChBD) of chitinase from Bacillus circulans. Introduction of ChBD to the Saz_CA had no major impact on the effect of ions or inhibitors on the enzymatic activity. The fusion protein exhibited no negative effects up to 60 °C, whilst the fusion partner appears to protect the enzyme from negative effects of magnesium. The prepared biocatalyst appears to be thermally activated at 60 °C and could be partially purified with heat treatment. Immobilisation attempts on different kinds of chitin-based support results have shown that the fusion enzyme preferentially binds to a cheap, untreated chitin with a large crystallinity index over more processed forms of chitin. It suggests significant potential economic benefits for large-scale deployment of immobilised CA technologies such as CO2 utilisation or mineralisation.

Highlights

The ever-increasing atmospheric concentration of CO2 and resulting climate change require development of new technologies for carbon capture, sequestration and utilisation
We describe the expression of codon-optimised carbonic anhydrase of Sulfurihydrogenibium azorense fused with a chitin binding domain (ChBD) of Bacillus circulans chitinase A1 in Escherichia coli, a simplified protein purification scheme based on thermal precipitation, assessment of ChBD binding properties to different chitin-based supports and the fusion domain effect on the enzyme properties
We constructed a thermostable fusion enzyme composed of the S. azorense Carbonic anhydrases (CAs) and B. circulans chitinase ChBD

Summary

Introduction

The ever-increasing atmospheric concentration of CO2 and resulting climate change require development of new technologies for carbon capture, sequestration and utilisation. Carbonic anhydrases are zinc metalloenzymes that catalyse carbon dioxide hydration and dehydration These biocatalysts are known to be one of the fastest biocatalysts in nature, with turnover numbers in millions of reactions per second [9,10,11,12] and as such could potentially make a massive contribution to the reduction of CO2 emissions if employed properly. Research on these remarkable proteins goes beyond environmental applications. In recent years research has been conducted for activators of these enzymes that could have a significant impact on both their environmental and medical applications [13,15] and could shed more light on important mechanisms, such as invasion, colonisation and pathogenicity of certain bacteria, all of which involve carbonic anhydrase action [15]

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