title: Covalent immobilization of invertase on polyurethane, plast-film and ferromagnetic Dacron.
abstract: Invertase was covalently immobilized on polyurethane (PU), inox plate covered with plast-film layer and ferromagnetic azide-Dacron. The immobilization processes, physico-chemical parameters and a model for coupling reactions were studied. The preliminary studies for selection of the support showed that the best activity was obtained for PU treated with HCl, polyethylenimine and glutaraldehyde (156.7+/-4.9 U/g support). All plast-film-invertase derivatives did not show activity and the Dacron-invertase derivative showed an activity of 105.39 U/g support. The invertase immobilized in presence of substrate (10% w/v sucrose) was the most efficient (832.74+/-1.48 U/g support). The optimal pH was shifted from 4.5 (free enzyme) to 5.0 (immobilized derivative) and optimal temperature was not affected. Activation energy values of free enzyme, Dacron-invertase and PU-invertase were 32.4+/-0.34 kJ/mol, 33.4+/-0.36 kJ/mol and 44.0+/-0.67 kJ/mol, respectively. The PU-invertase could be used over 2 months without considerable activity loss (68.5% activity retention) and retained 12.6% (287.97+/-27.9U/g support) of the activity after five cycles.
authors: Laboratório de Imunopatologia Keizo Asami, Universidade Federal de Pernambuco (UFPE), 50780-901 Recife, Pernambuco, Brazil.
authors: P G
authors: PG
authors: Cadena
authors: R A S
authors: RA
authors: Jeronimo
authors: J M
authors: JM
authors: Melo
authors: R A
authors: RA
authors: Silva
authors: J L
authors: JL
authors: Lima Filho
authors: M C B
authors: MC
authors: Pimentel
mesh_terms: D001386:Azides / Q000737:chemistry; D001709:Biotechnology / Q000379:methods*; D002241:Carbohydrates / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000737:chemistry*; D005976:Glutaral / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008280:Magnetics; D008422:Materials Testing; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry; D043324:beta-Fructofuranosidase / Q000737:chemistry*
chemical_list: D001386:Azides; D002241:Carbohydrates; D004800:Enzymes, Immobilized; D006834:Hydrazines; D011093:Polyethylene Terephthalates; D011140:Polyurethanes; D011506:Proteins; C029424:hydrazine; D013395:Sucrose; D011094:Polyethyleneimine; D043324:beta-Fructofuranosidase; D005976:Glutaral