Carbonic anhydrase activity in acetate grownMethanosarcina barkeri

✍ Scribed by Marion Karrasch; Michael Bott; Rudolf K. Thauer

• Publisher: Springer
• Year: 1989
• Tongue: English
• Weight: 647 KB
• Volume: 151
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00414428

✦ Synopsis

Cell extracts (27000 x g supernatant) of acetate grown Methanosarcina barkeri were found to have carbonic anhydrase activity (0.41 U/mg protein), which was lost upon heating or incubation with proteinase K. The activity was inhibited by Diamox (apparent Ki = 0.5 mM), by azide (apparent Ki = I raM), and by cyanide (apparent Ki = 0.02 raM). These and other properties indicate that the archaebacterium contains the enzyme carbonic anhydrase (EC 4.2.1.1). Evidence is presented that the protein is probably located in the cytoplasm. Methanol or H2/CO2 grown cells of M. barkeri showed no or only very little carbonic anhydrase activity. After transfer of these cells to acetate medium the activity was "induced" suggesting a function of this enzyme in acetate fermentation to CO2 and CH4. Interestingly, Desulf obacter postgatei and Desulf o tomaculum acetoxidans, which oxidize acetate to 2 COz with sulfate as electron acceptor, were also found to exhibit carbonic anhydrase activity (0.2 U/rag protein).