Glucose isomerase, temperature

Figure 3(A). Comparison of temperature optima for activities of glucose isomerase, amylase, and >galactosidase. Enzymes were assayed with cell extract from xylose-grown cells. A 100% activity value corresponds to 0.60, 0.58, and 0.46 U/mg for glucose isomerase, amylase, and -galactosidase, respectively. Cell extracts in 50 mM sodium phosphate buffer (pH 7.0), 100 mM sodium acetate buffer (pH 5.5), and 100 mM sodium phosphate buffer (pH 6.0) for glucose isomerase, amylase, and -galactosidase, respectively, were preincubatcd at the indicated temperatures, prior to the assay for residual enzyme activities. Reprinted with permission from ref. 20. Copyright 1990 American Society for Microbiology.

Figure 3(B). Comparison of temperature optima for stabilities of glucose isomerase, amylase, and d-galactosidase. Reprinted with permission from ref. 20. Copyright 1990 American Society for Microbiology.

J. A. Roels and R. van Tilberg, Temperature dependence of the stability and the activity of immobilized glucose isomerase,... 

High-Fructose Corn Syrup (HFCS) occurs as a water white to light yellow, somewhat viscous liquid that darkens at high temperatures. It is a saccharide mixture prepared as a clear, aqueous solution from high-dextrose-equivalent corn starch hydrolysate by the partial enzymatic conversion of glucose (dextrose) to fructose, using an insoluble glucose isomerase preparation that complies with 21 CFR 184.1372 and that has been obtained from a pure culture fermentation that produces no antibiotics. It is miscible in all proportions with water. 

In general, D-glucose isomerases require a divalent cation such as Co2+, Mg +, or Mn2+ for their catalytic action.40 The D-glucose isomer-ases usually function well in the pH range of 6.5 to 8.5, and at temperatures from 40°C (104°F) to as high as 80°C (176°F), depending upon the source of the enzyme. 

Starch (i. e. high fructose, corn syrup, fuel ethanol, etc.) Amylases, pullulanases, glucose isomerases Acids High temperatures... 

Figure 4. ICI glucose isomerase characteristic life curve. Feed conditions temperature 60°C,...

Temperature Dependence of the Stability and the Activity of Immobilized Glucose Isomerase... 

Figure 5 shows the effect of pH at varying temperatures on the expressed activity of glucose isomerase isolated from Bacillus coagulans and immobilized on MPS. It may be noted that the optimum pH (measured at room temperature) is not affected by varying the temperature and that the per cent change of activity as a function of pH remains relatively constant with changing temperatures. Figure 6 is an Arrhenius plot of the pH 7.5 data in Figure 5. Using the formula In K = In A - E /RT an activation energy of 19.6 K cal/mole is obtained.

Figure 7. Half life study of glucose isomerase on Amerace flow-through reactor. Conditions pH—7.5, temperature—60° C. Substrate dextrose—w/w, MgSOi 7H,0—2 g/L, NaHSOs—1 g/L, NaHCO l g/L.

Abu-Reesh I, Faqir N (1996) Simulation of glucose isomerase reactor optimum operating temperature. Bioproc Eng 14 205-210... 

Faqir N, Abu-Reesh 1(1998) Optimum temperature operation mode for glucose isomerase operating at constant glucose conversion. Bioproc Eng 19 11-17 Greco G, Pirozzi, D, Maremonti M et al. (1993) The kinetics of enzyme inactivation. In van den Tweel W, Harder A, Buitelaar R (eds). Stability and stabilization of enzymes. Elsevier, Amsterdam, pp 429 35... 

Enzyme activity has a certain dependence on temperature, and the general enzyme has an optimal temperature, and immobilized enzyme is no exception. Compared to the solution enzyme, the optimum temperature of immobilized enzyme shows ups and downs. The study found that the aminoacylase was bound to DEAE-cellulose and DEAE-dextran using ion-binding, or embedded in crosslinked polyacrylamide gel. Thus, the immobihzed enzyme was prepared, and its optimum temperature was somewhat higher than that before the immobilization. When aminoacylase was immobilized by iodine acetyl cellulose with covalent binding, its optimum temperature was somewhat lower than that before the immobilization. When the glucose isomerase was boimd to porous resin with covalent binding. 

D-Glucose isomerase has been immobilized with retention of enzymic activity by water soluble carbodi-imide aided reaction with chitosan. By reaction with/adsorption on to a range of new polyphenolic resins, and as Strepto-myces phaeochromogenes cells in fine-particle form using radiation-induced polymerization at low temperatures with previously salted out hydrophilic monomers such as 2-hydroxyethylacrylate and 2-hydroxyethylmethacrylate. ... 

The immobilization of a-amylase, 3-D-galactosidase, and D-glucose isomerase by adsorption onto gallotannin coupled to aminohexyl-cellulose has been described.Conditions of the adsorption process studied included time of contact, protein concentration, salt concentration, pH, temperature, and buffer used. 

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