Methanosarcina class carbonic anhydrase

Iverson, T. M., Alber, B. E., Kisker, C., Ferry, J. G., and Rees, D. C. (2000). A closer look at the active site of gamma-class carbonic anhydrases High-resolution crystallographic studies of the carbonic anhydrase from Methanosarcina thermophila. Biochemistry 39, 9222-9231. 

Tripp BC, Ferry JG. 2000. A structure-function study of a proton transport pathway in a novel gamma-class carbonic anhydrase from Methanosarcina thermophila. Biochemistry 39 9232 0. 

Structure of y-Class Carbonic Anhydrase of Methanosarcina thermophila (Cam) A. Proposed C02 Hydration Mechanism for y-Class Carbonic Anhydrase... 

A structure-function study of a proton pathway in the y-class carbonic anhydrase from Methanosarcina thermophila was conducted in the work of Tripp and Ferry (2000). Four enzyme glutamate residues were characterized by site-directed mutagenesis. It was shown that Glu 84 and an active site residue, Glu 89, are important for CO2 hydration activity, while external loop residues, Glu 88 and Glu 89 are less important. Glu 84 can be substituted for other ionizable residues with similar pKa values and, therefore, participates in the enzyme catalysis not as a chemical reagent but as a proton shuttle. 

---