The use of poly(ethylene terephthalate)–poly(aniline) composite for trypsin immobilisation

This paper presents trypsin immobilisation on strips of poly(ethylene terephthalate)–poly(aniline), activated with glutaraldehyde (PET–PANIG) composite. The photomicrography of the material showed changes corresponding to the chemical modifications produced in the steps of synthesis. The immobilisation process was very efficient under optimal conditions (18.6%). The immobilised and free enzyme presented the same pH and temperature optimum. PET–PANIG-trypsin was able to hydrolyse casein, albumin, gelatine, and skimmed milk. Kmapp value for PET–PANIG-trypsin was very close to Km of the free enzyme for casein. Immobilised trypsin showed higher stability than the free enzyme, with 100% activity after 14 days of storage at 4 °C and 100% operational stability after 4 cycles of use.