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

Proc Natl Acad Sci U S A. 2014 Nov 18;111(46):16436-41. doi: 10.1073/pnas.1411461111. Epub 2014 Nov 3.

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.

Keywords: carbon capture; carbonic anhydrase; directed evolution.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.