THE ENTHALPIMETRIC DETERMINATION OF THE K-M AND V(MAX) OF THE UREASE-UREA SYSTEM FROM A SINGLE ENZYME REACTION PROGRESS CURVE

The hydrolysis of urea was carried out in the isoperibol calorimetric set. The reaction was initiated by addition of urease solution in the amount sufficient to complete the reaction within ca. 20 minutes. The registered progress curve of the reaction, Delta T vs t, was the basis for determination of the kinetic constants K-M and v(max) of the syst em. Two systems were studied: one in phosphate buffer and the other on e, less known, in Tris buffer, both at pH 7. In this report the cat or i metric technique is discussed as a possible tool used in kinetic stu dies of enzymatic reactions. Three possible linearization procedures a re evaluated.