Localization of carbonic anhydrase in the cytoplasmic membrane of Neisseria sicca (strain 19).

The carbonic anhydrase activity and the growth of Neisseria sicca 19 were inhibited by the sulfonamide acetazolamide (10(-5) M). Such inhibition was completely overcome by the addition of exogenous bicarbonate. Some carbonic anhydrase activity associated with the membranous envelope fraction of the cell was released when cells were broken by sonic treatment but not during cell breakage by high-pressure extrusion. After the selective solubilization (4 degrees C) of the inner membrane of envelopes by treatment with 1% sodium lauroyl sarcosinate, all detectable carbonic anhydrase activity was found in the soluble (inner membrane) fraction. After fractionation of the cell envelope into inner and outer membranes by treatment with ethylenediaminetetraacetate (EDTA) followed by sucrose density gradient centrifugation, the total and specific activity of carbonic anhydrase paralleled that of succinate dehydrogenase, an inner membrane enzyme marker. The Coomassie blue stained protein patterns after polyacrylamide gel electrophoresis of the bands from the sucrose density gradient provided confirmation that the inner and outer membranes had indeed been separated.