ISATIN INHIBITION OF RAT TESTICULAR ALKALINE-PHOSPHATASE - NON-ALLOSTERIC PHENOMENON

Isatin has been found to inhibit rat testicular alkaline phosphatase (EC 3.1.3.1) uncompetitively. The hyperbolic curve relating inhibition as a function of substrate concentration; the persistence of inhibition after the tertiary structure of the enzyme has been altered by heat denaturation, exposure to urea or papain digestion; the small changes in entropy, free energy and enthalpy in the presence of isatin, and the number of isatin molecules (n=1.29) combining with one molecule of enzyme indicate the non-allosteric nature of inhibition.