Directed evolution of an ultrastable carbonic anhydrase for highly efficient carbon capture from flue gas.

Alvizo, Oscar; Nguyen, Luan J; Savile, Christopher K; Bresson, Jamie A; Lakhapatri, Satish L; Solis, Earl O P; Fox, Richard J; Broering, James M et al. · Proc Natl Acad Sci U S A · 2014

basic_science · Level V

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Abstract

Carbonic anhydrase (CA) is one of nature's fastest enzymes and can dramatically improve the economics of carbon capture under demanding environments such as coal-fired power plants. The use of CA to accelerate carbon capture is limited by the enzyme's sensitivity to the harsh process conditions. Using directed evolution, the properties of a β-class CA from Desulfovibrio vulgaris were dramatically enhanced. Iterative rounds of library design, library generation, and high-throughput screening identified highly stable CA variants that tolerate temperatures of up to 107 °C in the presence of 4.2 M alkaline amine solvent at pH >10.0. This increase in thermostability and alkali tolerance translates to a 4,000,000-fold improvement over the natural enzyme. At pilot scale, the evolved catalyst enhanced the rate of CO2 absorption 25-fold compared with the noncatalyzed reaction.