Characterization of Chymotrypsin - i-Carrageenan complex in aqueous solution: a solubility and thermodynamical stability study.

WOITOVICH VALETTI, NADIA ; BOERIS VALERIA; PICÓ GUILLERMO

INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 52 p. 45 - 51

0141-8130

The aim of this study is to report the results of research work on the molecular mechanism of complex formation between chymotrypsin and a negatively charged natural strong polyelectrolyte, i- carrageenan, using spectroscopy techniques. The carrageenan?chymotrypsin complex showed a maximal non-solubility at pH around 4.50 with a stoichiometric ratio between 8 and 33 g of chymotrypsin per g of carrageenan. These values were depended on the enzyme concentration, pH and ionic strength medium. The insoluble complex was redissolved by modifying the pH and by a NaCl concentration around 0.2 M in agreement with a coulombic mechanism of complex formation. The non-soluble complex formation showed biphasic kinetics. A fast step was carried out around 10 s and a coulombic mechanism takes place, and a slower step of around 120 s, where participate only Van der Waals forces. The enzymatic activity of chymotrypsin was maintained even in the presence of carrageenan (0.005%, w/v)