[Purification and characterization of chloroplast carbonate dehydratase from leaves of Lactuca sativa (author's transl)].

Two isoenzymes of carbonate dehydratase were identified in green leaf tissue of Lactuca sativa. Their molecular weights were found to be 195 000 and 250 000. The lighter isoenzyme (I) was further characterized. It is localized in the chloroplast fraction. With polyacrylamide gel electrophoresis in the presence of dodecyl sulphate, subunits with a molecular weight of 34 000 and higher aggregates of this size could be detected. This is interpreted as an indication of an hexameric enzyme structure. The 900-fold purified polymer contained 5 - 6 atoms of zinc. Amino acid composition and inhibition by acetazolamide (Diamox), cyanide, nitrate, azide and ferricyanide are described.