DPP IV/hCA II-IN-1 is a potent and selective dipeptidyl peptidase IV (DPP IV) and carbonic anhydrase ( CA ) inhibitor with an IC 50 value of 0.049 μM for DPP IV and with K i values of 0.0361, 0.0428, 0.0941, 0.1328, 0.2615, and 3.034 μM for CA II, CA VB, CA VA, CA IX, CA I , and CA IV, respectively.