Stability of Carbonic Anhydrase in Leaves of Vitex negundo in Karst Areas of Southwest China

This paper describes the determination on the activity of carbonic anhydrase (CA, EC4.2.1.1) of plant species in karst areas of Southwest China. CA was extracted from leaves of Vitex negundo. The thermostability of CA and the effects of anions and metallic ions on CA activity were investigated. CA activity was stable at different temperatures and relatively stable when the concentration of Ca²⁺ and Mg²⁺ was lower than 10 mmol·L⁻¹; Co²⁺ and Cu²⁺ lower than 0.001 mmol·L⁻¹; and Zn²⁺, Mn²⁺, NO₃⁻, Cl⁻, Br⁻, I⁻ and NO₂⁻ lower than 0.01 mmol·L⁻¹. CA could be activated by Ca²⁺ and Mg²⁺ at 0.001~0.01 mmol·L⁻¹. Thus, CA had a relative adaptability and could maintain the activity well in the ions condition of soilwater and karstwater.