• Korean Journal of Microbiology
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• v.40 no.3
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• pp.232-236
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• 2004

We investigated hydrogen peroxide resistance of Escherichia coli possessing acetyl xylan esterase(AxeA) of Streptomyces coelicolor A3(2). The induction of AxeA production by isopropyl-$\beta$-thiogalactoside was confirmed by SDS-polyacrylamide gel electrophoresis. The differences in growth between induced and non-induced E. coli were determined by the changes in optical density of cultures after hydrogen peroxide treatment The lethal effect of hydrogen peroxide was observed for non-induced cultures at all concentrations tested in this study (lmM, 2.5mM and 5mM). However, cultures induced for AxeA production resisted the lethal effect, except at 5mM where cells were killed irrespective of the AxeA production. The axeA induction increased survival against 1.5mM hydrogen peroxide from 59% to 74%. In addition, AxeA producing E. coli showed increased survival at $45^{\circ}C$, near maximum growth temperature. Therefore, it was concluded that AxeA conferred a cross-resistance upon the bacterium against both oxidative- and heat stress.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.569-574
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• 1989

These studies were conducted to investigate the purification and characterization of Kiwifruit protease, and the results obtained were as follows The protease was purified by ammonium sulfate fractionation, Sephadex G-100 filtration and DEAE-Sephadex A-50 column chromatography and purified enzyme gave a single protein band on polyacrylamide gel electrophoresis The specific activity of purified enzyme was 30,10 units/mg protein and the yield was 7.48. The purified enzyme showed a high affinity for casein and hemoglobin. The optimal pH and temperature for enzyme activity were 7.0 and $45^{\circ}C$, respectively. The enzyme activity was strongly inhibited by $HgCl_2,\;MnSO_4$. However. the enzyme was activated by cysteine and EDTA. The Michaelis constant for casein was calculated to be 50.5mg/ml according to the Line weaver-Burk method, and its molecular weight was determied as 23,500 by polyacrylamide gel electrophoresis.

• The Korean Journal of Zoology
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• v.17 no.3
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• pp.117-126
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• 1974

The amylase isozyme of the five strains of D. melanogaster in Korea(Yusu, Choongju, Jeju, Sinchon III and Sinchon IV) was examined by the polyacrylamide thin layer gel electrophoresis and the results obtained are presented below: 1. The most strains except the Sinchon IV show only one band $(Amy^1)$ in the zymograms. This implies that those strains may be homogeneous for amylase constitutions. 2. The Sinchon IV strain exhibits varisble band patterns (mostly $Amy^1,2$ and $Amy^1,4$) suggesting that this strain may be of heterogeneous amylase constitutions. 3. The $Amy^1$ strain may be the commonest one in the Korean D. melanogaster populations as in other countries. 4. The results of hybridization studies are hard to interpret. 5. Further studies will be extended to many other strains from various localities of Korea.

• The Korean Journal of Mycology
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• v.10 no.2
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• pp.67-73
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• 1982

The $(NH_4)_2\;SO_4$ (70%) treated crude enzymes from the culture filtrates of the$C-7^{+t}$ strain of Pyricularia oryzae which was grown on 2% CMC (carboxymethyl cellulose) for 8 days at $28^{\circ}C$ were chromatographied on Sephadex G-150 and DEAE-Sephadex A-25 columns. From the chromatography, three fractions of CMCase$(C_x)$ was examined using Na-CMC as substrate. The $C_x$ enzyme activity was optimal at pH 6.0 and $40^{\circ}C$, stable up to $40^{\circ}C$. The values of Km and Vmax of the enzyme were $2.8{\times}10\;mM$ and 5.9m moles/hour, respectively. The molecular weight determined by Sephadex G-150 column chromatography was around 80,000. Approximately sevenfold purified $C_x$ enzyme gave a single protein band on the polyacrylamide gel electrophoresis.

• The Korean Journal of Mycology
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• v.17 no.2
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• pp.57-65
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• 1989

The effect of various cellulosic and hemicellulosic substrates on the induction of cellulase and xylanase complexes in Aapergillus nidulans was investigated. The most efficient substrates for the induction of cellulase and xylanase complexes were carboxymethylcellulose for endoglucanase, cellobiose for ${\beta}-glucosidase$, and xylan for endoxylanase and ${\beta}-xylosidase$, respectively. However, the mixtures of these substrates, especially CMC-xylan and CMC-xylan-laminarin mixture, were much more effective not only for the enhancement of the biosynthesis of all the cellulase and xylanase complexes but also for the balanced production of these enzyme components than individual substrate. The polyacrylamide gel electrophoresis followed by activity staining showed the variation in the patterns and relative intensity of ${\beta}-glucosidase$, endoglucanase and endoxylanase components in individual enzyme preparations from A. nidulans cultures grown on different substrates. These results suggest that the biosynthesis is of cellulase and xylanase systems in A. nidulans is regulated in coordination at the level of induction.

• Korean Journal of Microbiology
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• v.26 no.3
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• pp.197-206
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• 1988

An outer membrane-associated 2-furaldehyde dehydrogenase, catalyzing the oxidation of 2-furaldehyde to 2-furoic acid from Klebsiella pneumoniae was purified to homogeneity and characterized. The enzyme showed its highly specific dependency on $\beta$-$NAD^{+}$. Enzyme activity was monitored during purification by using substrate 2-furaldehyde and coenzyme $\beta$-$NAD^{+}$ by means of high performance liquid chromatography. The outer membrane was successfully collected by the methods of Percoll density gradient ultracentrifugation and ultracentrifugation after preferential solubilization of the membrane with $Mg^{2+}$ and Triton X-100. The enzyme was purified by the series of procedures including extraction of outer membrane protein with EDTA and lysozume, and fractionation by column chromatography on QAE-Sephades Q-50, and subsequently Sephadex G-100. The enzume showed its optimal activity at $85^{\circ}C$, pH 9.5, and in the presence of 1.5% (vol/vol) Triton X-100. The enzyme exhibited a native molecular size of 88,000 by nondenaturing polyacrylamide gel electrophoresis and had an apparent Km of 4.72mM for 2-furaldehyde.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.5
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• pp.779-784
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• 1995

The effective production of 5'-GMP(5'-Guanylic acid) by immobilized 5'-GMP producing fusant RC102(intergeneric protoplast fusion between Brevibacterium ammoniagenes ATCC21263 and Corynebacterium glutamicum ATCC21171) was investigated. The Fusant RC102 was immobilized by entrapping in -carrageenan, agar, polyacrylamide or Ca-alginate. 3% k-carrageenan was selected as the most suitable matrix. In the production of 5'-GMP using the immobilized whole cells of fusant RC102, the optimum conditions were $32^{\circ}C$, pH 8.0, $30\mu\textrm{g}/L\;of\;Mn^{2+},\;1{\times}10^{-6}%\;of\;Zn^{2+}$. In order to use fermentation medium containing CSL(Corn Steep Liquor) plentiful in $Mn^{2+}$, the optimum conditions of penicillin G, D-cycloserine and POESA(polyoxyethylene stearylamine) for production of 5'-GMP were 0.8unit/ml, 0.8unit/ml, 0.8unit/ml and 5mg/ml, respectively. Cationic surfactant, POESA was effective and superior to the antibiotics, penicillin G or D-cyloserine in 5'-GMP productivity. The condinuous fermentation using immobilized fusant RC102 showed that 5'-GMP productivity was stable for more than 15 days.

• Applied Biological Chemistry
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• v.42 no.1
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• pp.39-44
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• 1999

Protein profiles of beef loin were constructed by comparing two-dimensional gel electrophoresis patterns of the proteins from different growth stages of Hanwoo, Korean cattle. Proteins from the lean muscle of 0, 6, 12 and 24 months old Hanwoo were separated by isoelectric focusing (IEF) on 16 cm tube gels, and further processed second dimensionally by 12% SDS-polyacrylamide gel electrophoresis (PAGE) using $18{\times}20$ cm gel. Proteins with pI values ranging 3.0 to 9.0 and molecular weight of 15 to 100 kDa could be clearly detected on gel by silver staining. Interestingly, many of the proteins significantly increased and decreased during growth happened to be low molecular ones. To isolate the increased proteins, the soluble proteins were obtained from the tissue by 1% Triton X-100 extraction, then, fractionated by 30% and 50% ammonium sulfate. The isolation condition of each particular protein was determined. According to the conditions, two of the increased proteins were isolated, and transferred to PVDF membrane and microsequenced.

• Microbiology and Biotechnology Letters
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• v.16 no.5
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• pp.389-392
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• 1988

A clone pSL 2-1, which is a recombinant plasmid believed to contain the mosquitocidal crystal-line protein gene of the Bacillus sphaericus 1593, was expressed in Escherichia coli JM83 and the product of the clone was purified and identified. The unsolubilized mosquitocidal crystal proteins from the B. sphaericus had formed 43, 58, 64, 100, 113, and 130 Kd bands in the SDS-polyacrylamide gel, but the NaOH-solublized proteins at pH 12 formed 2 protein bands of 43- and 64Kd in the gel because the larger protein (precursor) bands were cleaved. The products of the pSL 2-1 clone was purified by Sephadex G-200 and only the fractions having lethal activity to the 3rd in-star larvae of mosquito Culex pipiens were analyzed by the gel. The only single protein band of 42 Kd toxic to the larvae was formed. The major toxic protein being produced from the B. sphaericus 1593 and the pSL 2-1 clone was found to be the 42 Kd.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.289-294
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• 1992

Twenty-four bacterial strains among alkalophillic bacteria isolated from soil samples were examined for the presence of type II restriction endonuclease in aerobic culture. One strain was found to contain specific enzyme to cleave lambda DNA. The characteristics of this microorganism is the ability to grow well in alkalophilic and high temperature condition, that is at pH 10.3 and $50^{\circ}C$. This strain was tentatively identified to Bacillus alkaloPhilus subsp. halodurans when morphological, physiological and biochemical characteristics were examined. The enzyme was purified from crude extract by streptomycin sulfate, ammonium sulfate precipitation, which was followed by DEAE-cellulose and phosphocellulose ion exchange column chromatography, and the subunit molecular weight was about, 32,000 daltons by polyacrylamide gel electrophoresis containing 0.1% SDS.