• Korean Journal of Food Science and Technology
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• v.11 no.3
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• pp.192-199
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• 1979

With cells of Streptomyces spp K-45 isolated from soil, the immobilization of glucose isomerase by a series of treatments ; heat, carefully manipulated drying, extrusion with a thickening agent, and glutaraldehyde-induced crosslinking, was presented. This was aimed to obtain a mechanically stable form of whole cell containing glucose isomerase. The resulted pellet form had a good mechanical strength, compared with a commercial product, and showed 26 % of the activity recovery. The specific activity was 48.1 units per g of the dry material. The immobilized glucose isomerase generally showed properties similar to those of the soluble enzyme ; optimal pH at $7.5{\sim}9.0$, optimal temperature at $80{\sim}85^{\circ}C$, activation energy of 10.9 kcal/mole, and $K_m$ for glucose of 10.9M. The immobilized enzyme was very thermostable and pH stable.

• The Korean Journal of Food And Nutrition
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• v.2 no.1
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• pp.1-11
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• 1989

Glucose isomerase (E.C.5.3.1.5) which reversibly catalyzes reaction between D-glucose and D-fructose was demonstrated in cell free extracts of alkalophilic Streptomyces sp. B-2 isolated from soil The optimum temperature, pH, and pH stability were 6$0^{\circ}C$, 10.5, and 7.8, respectively. The production of Gl in xylose and yeast extract was higher than that of other carbon source and nitrogen source. The Gl production was affected by Co2+ and Mg2).

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.117-120
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• 1996

To enhance cellulose hydrolysis f Humicola insolens cellulase (HIC) was empolyed with immobilized glucose isomerase(IGI). Optimun pH and temperature for HIC were 6.5 and 55$^{\circ}C$, respectively, whereas those for IGI were 7.0 and 60$^{\circ}C$, respectively. Optimun loading size of IGI was 200mg(130 untis) with 15units of HIC. Reaction conditions were determined to be as follows: 55$^{\circ}C$,pH 6.5, HIC 15 units and IGI 130 units. After 24h hydrolysis, more than 65% of avicel was converted to glucose and fructose; in contrast, the conversion ratio of control was 40%.

• Journal of Microbiology
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• v.43 no.1
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• pp.34-37
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• 2005

In the present study, the xylA gene encoding a thermostable xylose (glucose) isomerase was cloned from Streptomyces chibaensis J-59. The open reading frame of xylA (1167 bp) encoded a protein of 388 amino acids with a calculated molecular mass of about 43 kDa. The XylA showed high sequence homology (92% identity) with that of S. olivochromogenes. The xylose (glucose) isomerase was expressed in Escherichia coli and purified. The purified recombinant XylA had an apparent molecular mass of 45 kDa, which corresponds to the molecular mass calculated from the deduced amino acid and that of the purified wild-type enzyme. The N-terminal sequences (14 amino acid residues) of the purified protein revealed that the sequences were identical to that deduced from the DNA sequence of the xylA gene. The optimum temperature of the purified enzyme was $85^{\circ}C$ and the enzyme exhibited a high level of heat stability.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.405-412
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• 1991

The enzymes were immobilized by treating the microbial cells in 0.05% chitosan and 0.28% glutaraldehyde solution. The activity of immobilized cell was about 535 IGIC/g. Glucose isomerase was purified by 6.5 times after homogenization using 60% $(NH_4)_2S0_4$ fractionation, DEAE-cellulose and Sephadex G-150 gel filtration. The molecular weight of enzyme was about 140,000 when it was measured by HPLC and the purified enzyme had only one band by electrophoresis. It showed good enzyme activity at pH 7.5 and $75^{\circ}C$. The optimum conditions for enzyme reactions were shifted to pH 7.0 and $80^{\circ}C$ when the enzyme was immobilized. The enzyme reaction was activated by the addition of 5~10 mM magnesium ion and the thermostability was improved by the addition of 0.25 mM cobalt ion. The enzyme activity was competitively inhibited by sugar alcohols.

• Microbiology and Biotechnology Letters
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• v.7 no.1
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• pp.9-14
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• 1979

The hemicellulose fraction of ryegrass straw was extracted with NaOH and used for production of glucose isomerase by Streptomyces flavogriseus. Up to 25％ crude hemicellulose (20％ as pentosan) could he obtained by treating straw with 1 to 24％ NaOH. The yield of hemicellulose was increased proportionately with increasing NaOH concentration up to 4％, but the rate of increase was slowed thereafter. The optimum condition for hemicellulose extraction from ryegrass straw was to treat straw with 4％ NaOH for 3hrs at 9$0^{\circ}C$ or 24hrs at 3$0^{\circ}C$. Highest level of glucose isomerase activity (3.04 units/ml culture) was obtained when the organism was grown for 2 days at 3$0^{\circ}C$ on 2％ straw hemicellulose. The organism also produced a good quantity of glucose isomerase on xylan, xylose or H$_2$SO$_4$-hydrolysate of straw. The hemicellulose-extracted straw residue could be used as animal feed, because the residue had 75％ higher digestibility and 20％ better feed efficiency for weanling meadow voles than the untreated straw.

• Korean Journal of Microbiology
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• v.18 no.2
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• pp.59-66
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• 1980

Two strains S-P and S-P-2, both Streptomyces sp., have been isolated and were found to have relatively high specific enzyme activity compared to other organisms reported. The specific activity of the enzyme produced from these two strains were 0.25 and 0.2 international units respectively. The productivity of the enzyme achieved was about 50 IU/l/hr. Glucose isomerase form these strains was found to be stable under the temperature of heat treatment (at $65^{\circ}C$) for fixation of enzyme inside the dell. This organism has an advantage in that it did not require toxic metalic ion for enzyme activity and could utilize xylan in leu of xylose as an inducer. The optimal temperature and pH of enzymatic reaction purpose of using these data for the optimal operation and designing of enzyme reactor system. The reaction mechanism was found to follow the single substrate reversible reaction kinetics. The kinetic constants determined experimentally are : $K_{mf}=0.33M,\;K_{mb}=1.0M,\;V_{mf}=0.88{\mu}mole\;per\;min.,\;V_{mb}= 2.96{\mu}mole\;per\;min.\;and\;K_{eq}=0.74.

• Korean Journal of Microbiology
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• v.15 no.1
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• pp.9-19
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• 1977

Xylone isomerase (D-xylose ketol-isomerase, EC 5,3,1,5) have been demonstrated in the cell-free extracts of Stroptomuces canus and Streptomuces malachiticus grown in the presence of xylose. Xylose, glucose and ribose served as substrates for the enzymes of the two strains with respective $K_m$ values of 22, 130, 290 mM (S. canus) and 7,83,637 mM(S.malachiticus), and $V_max$ values of 1,000, 0.087, $\0.0222{\mu}moles/min/mg$ protein (S. canus) and 0.312, 0.083, 0.500.$\mu$moles/min/mg protein (S. malachiticus). L-Rhammose was also isomerized by the crude enzyme solutions of the two strains. The maximal activities of the two xylose-isomerases were observed at pH 7.5 and $75^{\circ}C$. The xylose isomerase activities of the two strains were activated two-three times by $Mg^{++}\;and\;Co^{++}$ as that of control, partially activated by $Ba^{++}$ and inhibited by $Ni^{++},\;Ca^{++}\;and\;Zn^{++}\$. Particulary, the addtion of $Mn^{++}$ stimulated xylose-isomerizing activities, but inhibited glucose-isomerizing activities in both strains. However, $Cu^{++}$ inhibited xylose-isomerizing activities, while stimulated glucose-isomerizing activities of the enzymes.

• Korean Journal of Microbiology
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• v.21 no.2
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• pp.51-60
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• 1983

Cultural characteristics of Strptomyces griseolus isolated from the soil were investigated. This strain was disclosed to utilize D-xylose, and D-glactose in preference order as a carbon source with the formation of glucose isomerase. The addition of sweet potato starch also proved effective promoting the total enzyme activity measured at 29% higher than the control. Corn cob, one of waste agricultural resources, was hydrolyzed in 2~3% $H_2SO_4$ solution at $100^{\circ}C$, 3~5 hours to produce a xylose syrup which gave rise to the recovery of 19.9% in a batch system and 28.2% in a repeated system. By the addition of both 2% of xylose syrup(Be'28) prepared by and us 65% of corn steep liquor (total nitrogen 1.2%), enzyme induction was maximized. The enzyme activity was stimulated by the xylose and the cell growth by the C.S.L. Also, remarkable increase of enzyme activity was noticed by the addition of protein acid hydrolysate 86.2% higher than the control. $QO_2$ of the biomass cultured in 30L capacity jarfermentor recorded low oxygen requirement of 251.2 1/hr. Maximum activity of glucose isomerase was observed noted at the 9th hour after inoculation which is 2 hours faster than the stationery was observed noted at the 9th hour after inoculation which is 2 hours faster than the stationery phase of the biomass growth. Glucose isomerase from the strain was activated by adding the $Co^{++}\;and\;Mg^{++}$ with optimum temperature of $73^{\circ}C$ and pH of 7.2. Conversion ratio of 60% glucose to frutose was 42.5% after 70 hours reaction.

• KSBB Journal
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• v.10 no.1
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• pp.9-14
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• 1995

Continuous production of fructooligosaccharides from sucrose by a dual immobilized enzyme system of fructosyltransferase and glucose isomerase was studied in a column reactor. The optimal temperature and pH of the immobilized fructosyltransferase were $65^{\circ}C$ and 5.5, respectively. The activity of glucose isomerase was favorable as temperature and pH were increased within the ranges examined. However, both the immobilized enzymes were thermally unstable over $5^{\circ}C$, suggesting that long-term operation of the dual immobilized enzyme column should be carried out below $50^{\circ}C$. The optimum packing ratio of fructosyltransferase to glucose isomerase was found to be around 5/3. Under the optimized reaction conditions, the dual enzyme column was successfully operated for 40 days without any loss of initial enzyme activities, yielding 66% of fructooligosaccharides. Furthermore, the relative sweetness of fructooligosaccharides produced by a dual emzyme system was enhanced by 6% compared with that of fructosyltransferase alone.