• Microbiology and Biotechnology Letters
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• v.11 no.1
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• pp.47-52
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• 1983

The extracellular inulase produced by Aspergillus sp. C-58 was isolated by pH and charcoal treatment, precipitation with ammonium sulfate from the crude extract, and separated into 3 fractions (P-I, II, III) by DEAE-cellulose column chromatography in the ratio of 31.1:1.7:1 with respect to the activity. The ratio of inulase activity to sucrase activity of P-I, P-II and P-III fraction was 0.23, 0.24 and 1.1 respectively. The enzyme P-I fraction was purified 482 fold with a 22.8% yield by DEAE-Sephadex A-50, Sephadex G-75, Sephadex G-100 (1st and 2nd) column chromatography, and appeared homogeneous on polyacrylamide disc gel electrophoresis and ultracentrifugation.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.392-397
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• 1984

These experiments were conducted to investigate general enzymatic characteristics of two forms(glucoamylase I and glucoamylase II) of the purified glucoamylase produced by Rhizopus oryzae. Molecular weights of glucoamylase I and glucoamylase II estimated by Sephadex G-100gel filtration, were approximately 101,000 and 115,000, respectively, and those estimated by SDS-polyacrylamide gel electrophoresis being 120,000 and 127,000, respectively. Isoelectric points of the above enzyme were pH 7.25 and pH 7.75. The optimum temperature was $50^{\circ}C$ and the enzyme was stable below $45^{\circ}C$. Optimum pH of both glucoamylase I and glucoamylase II was about pH 5.0. The stable pH range of them were pH 3.5-8.0 and 4.5-8.0, respectively. Michaelis constants of glucoamylase I and glucoamylase II toward souluble starch were 4.545 mg/ml and 5.560 mg/ml, respectively. $Hg^{++}$, $Pb^{++}$, p-CMB and IAA were inhibitors of glucoamylase I and $Hg^{++}$, $Mn^{++}$, p-CMB and IAA were inhibitors of glucoamylase II.

• Journal of Microbiology
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• v.37 no.1
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• pp.21-26
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• 1999

Two novel calcium-binding proteins, named CAB-I and CAB-II, have been isolated from Streptomyces coelicolor. Purification of the calcium-binding proteins involved heat treatment, fractionation with ammonium sulfate, acid treatment, anion exchange and hydrophobic interaction column chromatography, FPLC gel filtration, and preparative isoelectric focusing. A chelex competitive assay and 45Ca autoradiography verified the calcium-binding ability of the proteins. The major band CAB-II has an apparent molecular weight of 26,000 determined by SDS-polyacrylamide gel electrophoresis and 340,000 determined by gel filtration. The isoelectric point of this molecule showed the acidic nature of the molecule. N-terminal amino acid sequence analysis shows homology to rat Ca2+/calmodulin-dependent protein kinase-II (CAB-II) and yeast phosphoprotein phosphatase (CAB-I).

• Korean Journal of Microbiology
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• v.32 no.4
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• pp.297-300
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• 1994

About thirty bacterial strains of actinomycete isolated from the soil were examined for the presence of restriction endonuclease activity. Streptomyces diastatochromogenes, which was identified previously, was found to contain restriction endonuclease activity. The purification of this enzyme, SdiI, was carried out via streptomycin sulfate precipitation and ammonium sulfate fractionation followed by hydroxylapatite column chromatography. Sephacryl S-200 HR column chromatography and second hydroxylapatite column chromatography. SDS-polyacrylamide gel electrophoresis of the active protein (purified from various column chromatography) resulted in 35,000 Da protein.

• Korean Journal of Food Science and Technology
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• v.16 no.3
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• pp.322-328
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• 1984

These experiments were conducted to purify the glucoamylase produced by Rhizopus oryzae. Two forms of glucoamylase (GI and GII) from Phizopus oryzae were purified by $(NH_2)_2SO_4$ fractionation, acetone fractionation and successive column chromatography on DEAE-cellulose and CM-cellulose. The specific activities of GI and GII toward soluble starch were 157.6 U/㎎. protein (37.5 fold of crude extract), and 164.7 U/㎎. protein (39.2 fold of curde extract), respectively, and the yields of them were 4.3% and 3.8%, respectively. The two purified enzymes have shown a single band by polyacrylamide disc gel electrophoresis and SDS-polyacrylamide gel electrophoresis. The protein bands of their electrophoresis gel were revealed to have glucoamylase activity by iodine staining and were proved to be glycoprotein by periodic acid Schiff's staining.

• Microbiology and Biotechnology Letters
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• v.14 no.6
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• pp.447-453
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• 1986

The culture filtrate of thermophilic alkalophilic Bacillus K17 strain contained two types of xylanases were purified by ammonium sulfate fractionation, DEAD-Sephadex A-50 column chromatography, CM-Sephadex C-50 column chromatography and Sephadex G-100 gel filtration. The purified enzymes were found to be homogeneous by sodium dodecyl sulfate and disc polyacrylamide gel electrophoresis. Xylanase I and II were characterized with respect to molecular weight, optimal temperature and pH, thermal and pH stability, and Michaelis constant. Xylanase II was more active and stable, and showed greater substrate affinity and molecular weight than xylanase I. The activities of xylanases I and II were inhibited by Cu$^{++}$, Ag$^+$, Hg$^{++}$ and Fe$^{++}$. Xylanase I hydrolyzed xylan to yield xylobiose and higher amount of xylooligosaccharides, but xylanase II produced xylose other than xylobiose and xylooligosacchrides.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.239-246
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• 2005

Some characteristics of two forms of glucoamylase (glucan 1 A-$\alpha$-glucosidase, EC 3. 2. I. 3) purified from Aspergillus coreanus NR 15-1 were investigated. The enzymes were produced on a solid, uncooked wheat bran medium of A. coreanus NR 15-1 isolated from traditional Korean Nuruk. Two forms of glucoamylase, GA-I and GA-II, were purified to homogenity after 5.8-fold and 9.6-fold purification, respectively, judged by disc- and SDS-polyacrylamide gel electrophoresis. The molecular mass of GA-I and GA-II were estimated to be 62 kDa and 90 kDa by Sephadex G-1OO gel filtration, and 64 kDa and 91 kDa by SDS-polyacrylarnide gel electrophoresis, respectively. The optimum temperatures of GA-I and GA-II were 60$^circ$C and 65$^circ$C, respectively, and the optimum pH was 4.0. The activation energy (Ea value) of GA-I and GA-II was 11.66 kcal/mol and 12.09 kcal/mol, respectively, and the apparent Michaelis constants (K_{m}) of GA-I and GA-II for soluble starch were found to be 3.57 mg/ml and 6.25 mg/ml, respectively. Both enzymes were activated by 1 mM Mn^{2+} and Cu^{2+}, but were completely inhibited by 1 mM N­bromosuccinimide. The GA-II was weakly inhibited by 1 mM p-CMB, dithiothreitol, EDTA, and pyridoxal 5-phosphate, but GA-I was not inhibited by those compounds. Both enzymes had significant ability to digest raw wheat starch and raw rice starch, and hydrolysis rates of raw wheat starch by GA-I and GA-II were 7.8- and 7.3-fold higher than with soluble starch, respectively.

• Korea-Australia Rheology Journal
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• v.11 no.4
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• pp.275-278
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• 1999

Soft polymeric materials have gained importance in recent years, namely in food, pharmaceuticals, photographic media, adhesives, vibration dampeners and superabsorbers (to name a few), but also as inter-mediates for selforganization of molecules or supramolecules into long range order. Many of these soft materials are close to their gel point, i.e. they are liquids just before reaching their gel point or they are solids which have barely passed the gel point. New rheological methods need to be developed for the understanding of these soft materials; the typical liquid properties (viscosity) and typical solid properties (modulus) are not applicable since they diverge at the gel point. This will be discussed in the following. Fortunately, chemical gelation experiments with model polymers has given insight into the behavior at the gel point (Winter and Mours, 1997). This knowledge of the critical gel provides us with a reference state when working with soft polymeric materials. Chemical gels will serve as model materials for the exploration of physical gels. A novel method for detecting the gel point has been proposed: the instant of liquid-to-solid transition(gel point) is marked by the crossover of the normalized dynamic moduli G'/cos($n_c$$\pi$/2) and G"/sin($n_c$$\pi$/2).>/2).

• Corrosion Science and Technology
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• v.17 no.1
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• pp.30-36
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• 2018

The high rate of corrosion of magnesium alloys makes it limited for industrial applications. Therefore, surface treatment is required to enhance their corrosion resistance. In our study, a chemical conversion coating for protecting the corrosion of the magnesium alloy, AZ31B, was prepared by using a phosphate-permanganate solution. The chemical conversion coating had a limited protection ability due to defects arising from cracks and pores in the coating layer. The sol-gel coating was prepared by using trimethoxymethylsilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors, and aluminum acetyl acetonate as a ring opening agent. The corrosion protection properties of sol-gel and conversion coatings in 0.35wt% NaCl solution were measured by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test. The EIS results indicated that the resistance of the chemical conversion coating with the sol-gel coating was significantly improved through the sol-gel sealed phosphate-permanganate conversion coating. The results of the potentiodynamic polarization test revealed that the sol-gel coating decreased the corrosion current density ($I_{corr}$). The SEM image showed that the sol-gel coating sealed conversion coating and improved corrosion protection.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.17-24
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• 1995

The TEA complex polymeric sol was prepared by the alkoxide sol-gel method. The purpsoe of this experiment was to vefity the particle shape in the sol from the investigation of the rheological properties. TEA retarded hydrolysis rate by the reaction with alkoxide enough to make a stable transparent sol in the wide range of composition. From the results of the viscosity change with time, the optimum mole ratio for spinning was selected as 0.5 mole of TEA, 3 mole of H2O and the optimum viscosity was 104 cPs. The rheological behavior of the sol showed that the particle shape in the sol was linear, which was adequate for fiber drawing.