Study on Enzymatic Reaction Kinetics Catalyzed by Free and Sol-gel Immobilized Formaldehyde Dehydrogenase

Formaldehyde dehydrogenase(FADH) is immobilized by sol\|gel process with the encapsulation rate of FADH exceeds 98%.The enzymatic conversion of formic acid to formaldehyde was carried out under neutral pH and low temperature using the free and immobilized FADH as the catalysts and NADH as the electron donor. The enzymatic reaction catalyzed by free and immobilized FADH followed Michaelis\|Menten kinetics and the kinetic parameters were fitted by Dalziel's double\|substrate model. The reaction rate of the immobilized enzyme was about 50% of the reaction rate of the free enzyme. The values of the kinetics constants and Michaelis constants K\-m of the immobilized enzyme were higher than those of the free enzyme, indicating the presence of diffusion effects in the porous sol\|gel matrix.