Chymotrypsin - Eudragit Complex Formation

Abstract

Eudragit® L100 (EuL) and Eudragit® S100 (EuS) are synthetic polyanions differing on their electric charge density. They interact with chymotrypsin (ChTRP), a basic protein forming soluble and non-soluble complexes. The complex formation was studied by dynamic light scattering, isothermal titration calorimetry, native fluorescence emission, circular dichroism and thermodynamical thermal stability of the enzyme. EuS was able to bind 33 ChTRP molecules while EuL, 60. The binding of ChTRP to both Eu was slightly endothermic and the entropic factor was responsible for the soluble complexes formation. The ChTRP-Eu size increases with pH and the binding of ChTRP to Eu modifies the Eu hydrodynamic radium. The interaction of ChTRP with Eu did not modify its secondary or tertiary structure. The thermal stability of ChTRP was increased when it interacted with both Eu.