Trypsin immobilization on discs of polyvinyl alcohol glutaraldehyde/polyaniline composite

Discs of polyvinyl alcohol cross-linked with glutaraldehyde (PVAG) were synthesized and covered with polyaniline activated with glutaraldehyde (PANIG). Trypsin was covalently immobilized on this composite yielding a preparation containing 21.1 units per disc. The FT-IR spectra of the discs showed bands of PVA (3300 cm−1, 2930 cm−1 and 1440 cm−1) and PANI (1594 cm−1 and 1100 cm−1). The best immobilization conditions were: trypsin concentration at 0.2 mg mL−1, pH 7.6 and 60 min of incubation, similar to polyaniline–trypsin systems reported in the literature. The PVAG–PANIG–trypsin derivative showed an optimal pH and an optimal temperature of 7.0 and 35 °C, respectively. Hydrolysis of casein showed variations in the size of the products, revealing differences between the immobilized enzyme and the mechanism catalyzed by the native enzyme.