The rate of hydrolysis of p-nitrophenylacetate to p-nitrophenol is measured by spectrophotometry and isothermal microcalorimetry in Tris butTer 50 mM, pH 7.5 at 27 "c. The rate constants from both techniques were obtained 3.05x 10""min·1 and 3.00x 1 O""min" by spectrophotometry and microcalorimetry, respectively, which are in good coincidence with each other. This rate must be considered in measuring the kinetic characteristics of carbonic anhydrase, including K.., and V milt.  


A A SABOURY ,M U DAHOT ,N S SARRAF ,