Plant Carbonic Anhydrase

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Abstract
Evidence for the existence of a subst. in, or associated with, the green leaves of the elderberry bush (Sambucus canadensis) which catalyzes the reaction H2CO3 = H2O + CO2 is presented. It is similar to, but not identical with carbonic anhydrase. The activity of the subst. decreased rapidly after separation from the bush. It was not observed in other spp. The prepn. was made by grinding leaves with sand and water, and testing the resultant green suspension by the method of Meldrum and Roughton. Activity was expressed in units of E, an arbitrary velocity constant. In the test, 0.1 ml. of the suspension was placed in 4 ml. of substrate. All tests were made at 15[degree]C. The crude suspension was unstable. Activity was lost in 10-15 hrs. at 25[degree]C, or immediately upon boiling. Activity was preserved for several days by using 0.1 [image] SnCl2 instead of water in the suspension. The enzyme was purified by (NH4)2SO4 frac-tionation between the limits of 40 and 60% saturation. The enzyme behavior indicated that it is a protein. It was labile to heat and failed to pass through a dialyzing membrane. It was soluble and stable in 30% ethanol.

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