Three α-carbonic anhydrases, including human carbonic anhydrase I and II (hCA I, II) and sheep kidney carbonic anhydrase (sCA) were purified and kinetic interactions between the enzymes and oxytetracycline were investigated. The purification procedure was composed of preparation of homogenate (or hemolysate) and
affinity chromatography on Sepharose 4B-tyrosine-sulfanilamide. Oxytetracycline exhibited in vitro activatory effects on hCA I, II and sCA enzymes activity. Activity % values for this antibiotic were determined by plotting activity % vs. [A].