Isobaric titration of readine monolayers: kinetics of hydrolysis of glycerides by pancreatic lipase B.

The rate of lipolytic enzyme-catalyzed reactions yielding water-soluble products can be measured by isobaric titration. The method is based upon the measurement of the amount of substrate that must be added to a monalayer to maintain constant surface pressure during the course of the enzymatic reaction. The rate constants determined for the hydrolysis of trioctanion and 1,2-diotanoin by pancreatic lipase were identical with those determined by the variable surface pressure method and by a radioactive substrate technique. This direct titrimetric method has a wider dynamic range and more versatility for following surface reactions that previously described systems.