Beta carbonic anhydrase 1 (βCA1) is a metalloenzyme that catalyzes the reversible conversion of CO$_2$ and H$_2$O to HCO$_3^-$ and H$^+$. It is present mainly in plant leaves and is indirectly involved in photosynthesis, as it plays a role in the maintenance of CO$_2$ near the enzyme RuBisCO. Due to its presence in the leaves and ability to bind iodine, βCA1 is an important candidate for research on plant biofortification with iodine. In addition to inorganic and organic forms, iodine is also present in plants bound to proteins through certain amino acid residues. Most often it binds via a tyrosine amino acid residue. Biofortification of edible plants with iodine would increase the amount of iodine in the human diet consequently reducing its deficiency and associated diseases.
The purpose of our work was to successfully express the active form of the βCA1 protein from the plant Arabidopsis thaliana in the bacterial expression system. The expressed protein was purified by nickel affinity chromatography and the purification process was also optimized. To verify the activity of the expressed enzyme, we wanted to establish an activity test based on pH indicators.
We confirmed that the plant protein βCA1 can be expressed in the bacterial expression system and purified by Ni-affinity chromatography. We have established an activity test based on the pH indicator bromthymol blue, which has proven to be effective but still needs to be optimized. In the future, the activity test will be useful to compare the activity of iodized and non-iodized βCA1 enzymes.
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