Kinetics of glucose isomerization to fructose by immobilized glucose isomerase: anomeric reactivity of D-glucose in kinetic model.
The substrate specificity of immobilized D-glucose isomerase (EC 5.3. 1.5) is investigated with an immobilized enzyme-packed reactor. A series of isomerization experiments with alpha-, beta-, and equilibrated D-glucose solutions indicates that beta anomer as well as alpha anomer is a substrate of the glucose isomerase at pH 7.5 and 60 degrees C. For substrate concentration of 0.028 mol l(-1) (1% w/v), the initial conversion rate of alpha-D-glucose was 43% higher than that with equilibrated glucose at the same concentration and 113% higher than beta-D-glucose conversion rate. This anomeric reactivity of glucose isomerase is mathematically described with a set of kinetic equations based on the reaction steps complying with Briggs-Haldane mechanism and the experimentally determined kinetic constants. The proposed reaction mechanism includes the mutarotation and the isomerization reactions of alpha- and beta-D-glucose with different rate constants.
Lee
H S
HS
Department of Chemical and Biochemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575, USA.
Hong
J
J
D019747:Aldose-Ketose Isomerases / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005632:Fructose / Q000096:biosynthesis* / Q000737:chemistry; D005947:Glucose / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008956:Models, Chemical; D013302:Streptomyces / Q000201:enzymology; D013379:Substrate Specificity
D004800:Enzymes, Immobilized; D005632:Fructose; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase; D005947:Glucose