CARBONIC ANHYDRASE IN GREEN PLANTS

Abstract

Carbonic anhydrase was found in leaf extracts prepared from 19 of 22 land and aquatic plant species examined. The most active preparations were obtained from Spinacia oleracea L., Tetragonia expansa Thunb., Tropaeolum majus L., and Sambucus canadensis L. Carbonic anhydrase is located in the leaf cytoplasm. Previously conflicting observations concerning its intracellular localization have been reconciled experimentally. Plant carbonic anhydrase is strongly inhibited by M/1000 azide, M/1000 cyanide, and M/2000 sulphanilamide 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 four and five days was lowered by 30–50%. Very young leaves contain less enzyme than mature ...