CARBONIC ANHYDRASE IN GREEN PLANTS

Abstract
Carbonic anhydrase was found in leaf extracts prepared from 19 of 22 land and aquatic plant spp. examined. The most active prepns. were obtained from Spinacia oleracea, Tetragonia expansa, Tropaeolum majus, and Sambucus canadensis. Carbonic anhydrase is located in the leaf cytoplasm. Previously conflicting observations concerning its intracellular localization were reconciled experimentally. Plant carbonic anhydrase is strongly inhibited by [image]/1000 azide, [image]/1000 cyanide, and [image]/2000 sulfanilamide and is weakly inhibited by 2,4-dichlorophenoxyacetic acid, diethyldithiocarbamate, and o-phenanthroline. The white zones of variegated Tradescantia leaves contain 50% less carbonic anhydrase than their green counterparts. Albino barley leaves contain 75% less carbonic anhydrase than normal barley leaves of the same size and age. The carbonic anhydrase content of green leaves kept in darkness for 4 and 5 days was lowered by 30-50%. Very young leaves contain less enzyme than mature leaves. These results are discussed in relation to the possible role of carbonic anhydrase in photosynthesis.

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