Immobilization of glucose isomerase to ion‐exchange materials

Abstract

SummaryGlucose isomerase (D-XylOSe ketol-isomerase EC 5.3. I . 5 ) from Bacillus coagu~ans was partially purified and immobilized by adsorption to anion exchangers. The highest activities were obtained when the enzyme was adsorbed to DEAE-cellulose. On immobilization to DEAE-cellulose the measured optimum pH value for enzyme activity shifted from 7.2 to 6.8. There was no appreciable difference between the heat stabilities of soluble and immobilized enzyme. The K , Bpp values for the immobilized enzyme were found to be 0.25M in the presence of 0.01M Mg2+ and 0.19M with O.OO5M Mg2+, while those for the soluble enzyme were 0.11 and 0.17M, respectively. Under conditions of continuous isomerization of D-glucose, a decrease of activity with time was observed, but this decrease was less at a low Mg2+ concentration and was affected by column geometry. There were no appreciable diffusional limitation effects in packed-bed columns.

Immobilization of photochemically‐active chloroplasts onto diethylaminoethyl‐cellulose

“…Furthermore, the specific activities of the immobilized chloroplasts were higher than those of the free chloroplasts (table 1). This increase of the specific activity was similar to the observation with glucoamylase [7] and glucose isomerase [8] immobilized on DEAE-cellulose. However, it may be asked whether the higher activity observed in our immobilized chloroplasts was mainly caused by uncoupling of photophosphorylation.…”

“…Thus, we have found no improvement in thermal stability upon adsorption to DEAE-cellulose in contrast with the chloroplasts entraped within polyacrylamide gel [l] or within microcapsules [3]. A similar observation has been made with glucose isomerase immobilized on DEAE-cellulose [8]. Figure 4 illustrates the continuous photoreduction of DCIP catalyzed by immobilized chloroplasts with water as the electron donor.…”

“…In order to determine the maximum amount of chloroplasts and activities that DEAE-cellulose could hold, different concentrations of chloroplasts were added to the DEAE-cellulose by the methods in [8]. Figure 1 shows that the amount of activity retained onto the ion exchanger support varied depending on the chloroplasts added.…”

“…Diethylaminoethyl (DEAE)-cellulose, one of the anion exchangers, is commercially available and widely used as an ion exchanger for protein fractionation. It has already been used effectively as a substratum for various enzymes such as acid acylase [6], glucoamylase [7], glucose isomerase [8] and invertase [9]. We have investigated its application for preparation of immobilized chloroplasts with a high retention of photochemical activities.…”

Immobilization of Polysaccharide-degrading Enzymes

“…Experiments that typically identify diffusion-limitation problems, such as comparisons of the Arrhenius and Lineweaver~Burk plots for free versus immobilized enzymes, or measurement of reaction rates for the enzyme bound to support" of varying pore or particle sizes, have concluded that no appreciable diffusion limitation exists (S6ret:lsen and Emborg, 1989;Schafhauser and Storey, 1992b). Similarly, experiments conducted to assess the presence of external mass-transfer limitations, such as increasing the agitation speed of the bioreaclor, had minimal effect on the apparent kinetic properties of the immobilized glucose isomerase and, therefore, showed no restrictions on the catalytic efficiency of the immobilized enzyme (Huitron and Limon-Lason, 1978;Schatbauser and Storey, 1992b). However, Y.Y.…”