[Carbonic anhydrase of the alkaliphilic cyanobacterium Microcoleus chthonoplastes]. / Karboangidraza alkalofil'noi tsianobakterii Microcoleus chthonoplastes.

The activity of carbonic anhydrase (CA) was studied in different cell fractions of the alkaliphilic cyanobacterium Microcoleus chthonoplastes. The activity of this enzyme was found in the soluble and membrane protein fractions, as well as in intact cells and in a thick glycocalyx layer enclosing the cyanobacterium cells. The localization of CA in glycocalyx of M. chthonoplastes was shown by the western blot analysis and by immunoelectron microscopy studies with antibodies to the thylakoid CA from Chlamydomonas reinhardtii (Cah3). At least one of the CA forms occurring in M. chthonoplastes CA was shown to be an alpha-type enzyme. A possible mechanism of the involvement of the glycocalyx CA in calcification of cyanobacteria is discussed.