抄録
Lactosucrose synthesis from sucrose and lactose was carried out by using β-fructofuranosidase from Arthrobacter sp. K-1. The transfructosylation mechanism was found to be of an ordered bi-bi type in which sucrose was bound first to the enzyme and lactosucrose was released last. Hydrolysis side-reaction experiments indicated that the reactions were uncompetitively inhibited by glucose and lactose, while no inhibition by fructose was apparent. The overall reaction rates were formulated. The reaction rate constants, equilibrium constant, and dissociation and Michaelis constants were determined at 35°C and 50°C by fitting the experimental concentration changes with the calculated values by a nonlinear least-square method. The average relative derivation for the concentrations was 9.67%. The kinetic parameters were also calculated for 43°C and 60°C by assuming the Arrhenius law, and the course of reaction was predicted. The obtained reaction rate equations well represented the concentration changes during the experiment at all temperatures.
