The thermal and the combined high pressure–thermal inactivation kinetics of almond β-glucosidase (β-d-glucoside glucohydrolase, EC 18.104.22.168) were investigated at pressures from 0.1 to 600 MPa and temperatures ranging from 30 to 80 °C. Thermal treatments at temperatures higher than 50 °C resulted in significant inactivation with complete inactivation after 2 min of treatment at 80 °C. Both the thermal and high pressure inactivation kinetics were described well by first-order model. Application of pressure increased the inactivation kinetics of the enzyme except at moderate temperatures (50 to 70 °C) and pressures between 0.1 and 100 MPa where slight pressure stabilisation of the enzyme against thermal denaturation was observed. The activation energy for the inactivation of the enzyme at atmospheric pressure was estimated to be 216.2 ± 8.6 kJ/mol decreasing to 55.2 ± 3.9 kJ/mol at 600 MPa. The activation volumes were negative at all temperature conditions excluding the temperature–pressure range where slight pressure stabilisation was observed. The values of the activation volumes were estimated to be −29.6 ± 0.6, −29.8 ± 1.7, −20.6 ± 3.2, −41.2 ± 4.8, −36.5 ± 1.8, −39.6 ± 4.3, −31.0 ± 4.5 and −33.8 ± 3.9 cm3/mol at 30, 35, 40, 45, 50, 60, 65 and 70 °C, respectively, with no clear trend with temperature. The pressure–temperature dependence of the inactivation rate constants was well described by an empirical third-order polynomial model.
Netsanet Shiferaw Terefe, Paul Sheean, Susil Fernando, Cornelis Versteeg
Endothelial nitric oxide synthase polymorphism G298T in association with oxidative DNA damage in coronary atherosclerosis
Content Type Journal Article
Category Research Note
RAJESH G. KUMAR, Department of Genetics, Osmania Univers ... more
A micropropagation protocol was developed for multiplication of seedless lemon (Citrus limon L. cv. Kaghzi Kalan) using nodal explants. The maximum shoot regeneration was observed on low level of BAP (0.1 mg l−1) or kinetin (0.5 mg l−1). BA was recorded to be better than kinetin in terms of ... more
The objective of this study was to evaluate the activity, kinetic behavior, and thermal inactivation kinetics of peroxidase (POD) in aqueous extracts from two kinds of milk ripe stage corn, sweet corn and waxy corn. Optimum activities using guaiacol as the hydrogen donor were obtained for s ... more