Open AccessStructural and biophysical characterization of the α‐carbonic anhydrase from the gammaproteobacterium Thiomicrospira crunogena XCL‐2: insights into engineering thermostable enzymes for CO 2 sequestration
Author(s) -
DíazTorres Natalia A.,
Mahon Brian P.,
Boone Christopher D.,
Pinard Melissa A.,
Tu Chingkuang,
Ng Robert,
AgbandjeMcKenna Mavis,
Silverman David,
Scott Kathleen,
McKenna Robert
Publication year - 2015
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s1399004715012183
Subject(s) - thermostability , thermophile , enzyme , protein engineering , carbonic anhydrase , thermal stability , active site , extremophile , chemistry , mesophile , biochemistry , psychrophile , materials science , biology , organic chemistry , bacteria , genetics
Biocatalytic CO 2 sequestration to reduce greenhouse‐gas emissions from industrial processes is an active area of research. Carbonic anhydrases (CAs) are attractive enzymes for this process. However, the most active CAs display limited thermal and pH stability, making them less than ideal. As a result, there is an ongoing effort to engineer and/or find a thermostable CA to fulfill these needs. Here, the kinetic and thermal characterization is presented of an α‐CA recently discovered in the mesophilic hydrothermal vent‐isolate extremophile Thiomicrospira crunogena XCL‐2 (TcruCA), which has a significantly higher thermostability compared with human CA II (melting temperature of 71.9°C versus 59.5°C, respectively) but with a tenfold decrease in the catalytic efficiency. The X‐ray crystallographic structure of the dimeric TcruCA shows that it has a highly conserved yet compact structure compared with other α‐CAs. In addition, TcruCA contains an intramolecular disulfide bond that stabilizes the enzyme. These features are thought to contribute significantly to the thermostability and pH stability of the enzyme and may be exploited to engineer α‐CAs for applications in industrial CO 2 sequestration.