Highly thermostable carbonic anhydrase from Persephonella marina EX-H1: Its expression and characterization for CO2-sequestration applications

Abstract

The codon-optimized carbonic anhydrase gene of Persephonella marina EX-H1 (PMCA) was expressed and characterized. The gene with the signal peptide removed, PMCA(sp-), resulted in the production of approximately five times more purified protein than from the intact gene PMCA using an Escherichia coli expression system. PMCA(sp-) is formed as homo-dimer complex. PMCA(sp-) has a wide pH tolerance (optimum pH 7.5) and a high thermostability even at 100 degrees C (88 min of thermal deactivation half-life). The melting temperature for PMCA(sp-) was 84.5 degrees C. The apparent k(cat) and K-m values for CO2 hydration were 3.2 x 10(5) s(-1) and 10.8 mM. The activity of the PMCA(sp-) enzyme was enhanced by Zn2+, Co2+, and Mg2+, but was strongly inhibited by Cu2+, Fe3+, Al3+, Pb2+, Ag+, and Hg2+. PMCA(sp-) readily catalyzed the hydration of CO2, precipitating CaCO3 as calcite in the presence of Ca2+. (C) 2014 Elsevier Ltd. All rights reserved.