Characterization of invertase entrapped into calcium alginate beads.
A solution of 10 g/L of sodium alginate (Satialgine types used [Sanofi trademark]: SG800 and S1100 with manuronic/guluronic ratio of 0.5 and 1.2, respectively) containing invertase (0.08 g of protein/L) was dropped into 0.1 M CaCl2 solution buffered at pH 4.0, 7.0, or 8.0. The beads were left to harden in CaCl2 solution for 24 h. The high immobilization yield of 60% occurred with SG800 at pH 8.0. The activity of soluble and insoluble invertase was measured against pH (2.8-8.0), sucrose concentration (4.5-45 mM), and temperature (30-60 degrees C). Both forms presented an optimum pH of 4.6. However, the soluble invertase was stable at the overall pH interval studied, whereas insoluble invertase lost 30% of its original activity at pH > 5.0. At temperatures above 40 degrees C, the insoluble form was more stable than the soluble one. The kinetic constants and activation energies (Ea) for free invertase were KM = 41.2 mM, Vmax = 0.10 mg of TRS/(min.mL), and Ea 28 kJ/mol for entrapped invertase they were (KM)ap = 7.2 mM, (Vmax)ap = 0.060 mg of TRS/(min.mL), and (Ea)ap = 24 kJ/mol.
Arruda
L M
LM
Department of Biochemical and Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, University of São Paulo, Brazil.
Vitolo
M
M
D000464:Alginates / Q000494:pharmacology; D001672:Biocompatible Materials; D016503:Drug Delivery Systems; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000494:pharmacology; D020723:Glucuronic Acid; D006026:Glycoside Hydrolases / Q000494:pharmacology; D006603:Hexuronic Acids; D008863:Microspheres; D043324:beta-Fructofuranosidase
D000464:Alginates; D001672:Biocompatible Materials; D004800:Enzymes, Immobilized; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase