Kinetics and inhibition of carbonic anhydrase-catalyzed hydrolysis of 2-hydroxy-5-nitro-α-toluenesulfonic acid sultone: Comparison with reactions of other substrates

摘要: Abstract The catalytic activities of human red cell carbonic anhydrase (EC 4.2.1.1) isozymes B and C for the hydrolysis 2-hydroxy-5-nitro-α-toluenesulfonic acid sultone have been compared with their towards three other substrates. substrate specificity (measured as K cat / m ) either isozyme decreases in this order: CO 2 > acetaldehyde p -nitrophenyl acetate. Unlike hydration, enzyme is slightly more active than C. Despite these widely differing both regard to different substrates, inhibition constants anion sulfonamide inhibitors are nearly independent used. This suggests that binding sites substrates same or same. Earlier studies on from laboratories had underestimated intrinsic activity susceptibility B. We now find was due use acetonistrile solvent, which often contaminated cyanide, a powerful inhibitor anhydrase. by several industrial batches acetonitrile agrees completely spectrophotometrically determined cyanide content batches.