Glucose thermal inactivation

The effects of temperature both on the stability of the enzyme (26, 37, 41, 46) and on the catalytic reaction itself (46, 112) have been studied. The enzyme is considerably more labile to mild heating in the absence of substrates than is microsomal acid phosphatase (26, 37, 4U 46)-Glucose-6-P (26, 136), P, (26), glucose (136), PP, (119, 136), and various amino acids (136) protect to some degree against thermal inactivation as do certain metal chelators which inhibit the reaction (120). 

CPBR with chitin-immobilized (3-galactosidase (Illanes et al. 1998a) is presented to illustrate enzyme reactor design under modulated thermal inactivation. Diffusional restrictions are in this case negligible, the enzyme is inhibited by the product galactose competitively and neither glucose nor lactose at high concentrations are inhibitors (Illanes et al. 1990), so that Fig. 5.14 simplifies to the scheme in Fig. 5.18. 

Torulopsis ingeniosa yeast was found to possess an a-amylase strongly attached to the cell wall, its pH optimum being 5.5, its optimum temperature was at 50 C, and it was highly sensitive to thermal inactivation.The enzyme was found to be induced by starch, but the synthesis was not subject to a D-glucose effect. 

More recently, cellulase-producing bacteria have been intensively studied. A thermally stable teta-glucosidase has been cloned from Microbispora bispora (10) that retains most of its activity even after 48 hours at 60°C, whereas the Trichoderma reesei beta-glucosidase is completely inactivated after 10 minutes at 60 C (11). Furthermore, not only is the Microbispora bispora enzyme resistant to end product inhibition, it is actually activated by a range of glucose concentrations. 

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