ANALYSIS OF THE INTERACTIONS BETWEEN EUDRAGIT® L100 AND PORCINE PANCREATIC TRYPSIN BY CALORIMETRIC TECHNIQUES.

BRAIA, MAURICIO; TUBIO, GISELA; NERLI, BIBANA; LOH, WATSON; ROMANINI, DIANA

INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 50 p. 180 - 186

0141-8130

Flexible-chain polymers with charge (polyelectrolytes) can interact with globular proteins with a net charge opposite to the charge of the polymers forming insoluble complexes polymer-protein. In this work, the interaction between the basic protein trypsin and the anionic polyelectrolyte Eudragit® L100 was studied by using isothermal calorimetric titrations and differential scanning calorimetry. Turbidimetric assays allowed determining that protein-polymer complex was insoluble at pH below 5 and the trypsin and Eudragit® L100 concentrations required forming the insoluble complex. DSC measurements showed that the Tm and denaturalization heat of trypsin increased in the polymer presence and the complex unfolded according to a two-state model. ΔH° and ΔS° binding parameters obtained by ITC were positives agree with hydrophobic interaction between trypsin and polymer. However, ionic strength of 1.0 M modified the insoluble complex formation. We propose a mechanism of interaction between Eudragit® L100 and trypsin molecules that involves both hydrophobic and electrostatic interactions. Kinetic studies of complex formation showed that the interaction requires less than one minute achieving the maximum quantity of complex. Finally, a high percentage of active trypsin was precipitated (approximately 76 % of the total mass of protein). These findings could be useful in different protocols such as a protein isolation strategy, immobilization or purification of a target protein.