Prokaryotic carbonic anhydrases

摘要: Carbonic anhydrases catalyze the reversible hydration of CO(2) [CO(2)+H(2)Oright harpoon over left HCO(3)(-)+H(+)]. Since discovery this zinc (Zn) metalloenzyme in erythrocytes 65 years ago, carbonic anhydrase has not only been found virtually all mammalian tissues but is also abundant plants and green unicellular algae. The enzyme important to many eukaryotic physiological processes such as respiration, transport photosynthesis. Although ubiquitous highly evolved organisms from Eukarya domain, received scant attention prokaryotes Bacteria Archaea domains purified five species since it was first identified Neisseria sicca 1963. Recent work shown that widespread metabolically diverse both indicating a more extensive fundamental role prokaryotic biology than previously recognized. A remarkable feature existence three distinct classes (designated alpha, beta gamma) have no significant sequence identity were invented independently. Thus, are excellent examples convergent evolution catalytic function. Genes encoding enzymes with gamma predominating. All isozymes (including 10 human isozymes) belong alpha class; however, nine class genes thus far domain none domain. comprised chloroplasts monocotyledonous dicotyledonous well phylogenetically domains. isolated characterized methanoarchaeon Methanosarcina thermophila. Interestingly, contain one some even known classes. In addition, multiple same class. presence within underscores importance physiology; role(s) still largely unknown. Even though most information about function(s) primarily relates its cyanobacterial fixation, function cyanate degradation survival intracellular pathogens their host. Investigations into already led identification new (gamma) future research will undoubtedly reveal novel functions for prokaryotes.