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Brazilian Journal of Chemical Engineering

Print version ISSN 0104-6632On-line version ISSN 1678-4383

Abstract

CALSAVARA, L.P.V.; MORAES, F.F.  and  ZANIN, G.M.. Thermal stability and energy of deactivation of free and immobilized cellobiase. Braz. J. Chem. Eng. [online]. 2000, vol.17, n.4-7, pp.841-848. ISSN 0104-6632.  http://dx.doi.org/10.1590/S0104-66322000000400047.

Commercial cellobiase has been immobilized in controlled pore silica particles by covalent binding with the silane-glutaraldehyde method with protein and activity yields of 67% and 13.7%, respectively. Thermal stability of the free and immobilized enzyme (IE) was determined with 0.2% w/v cellobiose solution, pH 4.8, temperatures from 40 to 70°C for free enzyme and 40 to 75°C for IE. Free cellobiase maintained its activity practically constant for 240 min at temperatures up to 55°C. The IE has shown higher stability retaining its activity in the same test up to 60° C. Half-lives for free enzyme were 14.1, 2.1 and 0.17 h at 60, 65 and 70°C, respectively, whereas the IE at the same temperatures had half-lives of 245, 21.3 and 2.9 h. The energy of thermal deactivation was 80.6 kcal/mol for the free enzyme and 85.2 kcal/mol for the IE, confirming stabilization by immobilization.

Keywords : Thermal stability; immobilized enzyme; cellobiase; cellobiose.

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