Gustavo Ribeiro - Profile on Academia.edu (original) (raw)
Related Authors
Uploads
Papers by Gustavo Ribeiro
Biochemical Engineering Journal, 2011
The objective of this work was to compare the properties of free and immobilized -galactosidase ... more The objective of this work was to compare the properties of free and immobilized -galactosidase (Aspergillus oryzae), entrapped in alginate-gelatin beads and cross-linked with glutaraldehyde. The free and immobilized forms of the enzyme showed no decrease in enzyme activity when incubated in buffer solutions in pH ranges of 4.5-7.0. The kinetics of lactose hydrolysis by the free and immobilized enzymes were studied at maximum substrate concentrations of 90 g/L and 140 g/L, respectively, a temperature of 35 • C and a pH of 4.5. The Michaelis-Menten model with competitive inhibition by galactose fit the experimental results for both forms. The K m and V m values of the free enzyme were 52.13 ± 2.8 mM and 2.56 ± 0.3 g glucose /L min mg enzyme , respectively, and were 60.30 ± 3.3 mM and 1032.07 ± 51.6 g lactose /min m 3 catalyst , respectively, for the immobilized form. The maximum enzymatic activity of the soluble form of -galactosidase was obtained at pH 4.5 and 55 • C. Alternatively, the immobilized form was most active at pH 5.0 at 60 • C. The free and immobilized enzymes presented activation energies of 6.90 ± 0.5 kcal/mol and 7.7 ± 0.7 kcal/mol, respectively, which suggested that the immobilized enzyme possessed a lower resistance to substrate transfer.
Biochemical Engineering Journal, 2011
The objective of this work was to compare the properties of free and immobilized -galactosidase ... more The objective of this work was to compare the properties of free and immobilized -galactosidase (Aspergillus oryzae), entrapped in alginate-gelatin beads and cross-linked with glutaraldehyde. The free and immobilized forms of the enzyme showed no decrease in enzyme activity when incubated in buffer solutions in pH ranges of 4.5-7.0. The kinetics of lactose hydrolysis by the free and immobilized enzymes were studied at maximum substrate concentrations of 90 g/L and 140 g/L, respectively, a temperature of 35 • C and a pH of 4.5. The Michaelis-Menten model with competitive inhibition by galactose fit the experimental results for both forms. The K m and V m values of the free enzyme were 52.13 ± 2.8 mM and 2.56 ± 0.3 g glucose /L min mg enzyme , respectively, and were 60.30 ± 3.3 mM and 1032.07 ± 51.6 g lactose /min m 3 catalyst , respectively, for the immobilized form. The maximum enzymatic activity of the soluble form of -galactosidase was obtained at pH 4.5 and 55 • C. Alternatively, the immobilized form was most active at pH 5.0 at 60 • C. The free and immobilized enzymes presented activation energies of 6.90 ± 0.5 kcal/mol and 7.7 ± 0.7 kcal/mol, respectively, which suggested that the immobilized enzyme possessed a lower resistance to substrate transfer.