Kupriyanova E, Villarejo A, Markelova A, Gerasimenko L, Zavarzin G, Samuelsson G, Los DA, Pronina N
Extracellular carbonic anhydrase of the stromatolite-forming cyanobacterium Microcoleus chthonoplastes
Microbiology: 2007 153:1149-1156

Active extracellular carbonic anhydrases (CAs) were found inthe alkaliphilic stromatolite-forming cyanobacterium Microcoleuschthonoplastes. Enzyme activity was detected in intact cellsand in the cell envelope fraction. Western blot analysis ofpolypeptides from the cell envelope suggested the presence ofat least two polypeptides cross-reacting with antibodies againstboth {alpha} and beta classes of CA. Immunocytochemical analysis revealedputative {alpha}-CA localized in the glycocalyx. This {alpha}-CA has a molecularmass of about 34Â kDa and a pI of 3.5. External CAs showedtwo peaks of activity at around pHÂ 10 and 7.5. The possibleinvolvement of extracellular CAs of M. chthonoplastes in photosyntheticassimilation of inorganic carbon and its relationship to CaCO3deposition during mineralization of cyanobacterial cells arediscussed.

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