• Food Science and Biotechnology
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• 제16권5호
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• pp.663-674
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• 2007

Starches from different botanical sources differ in the ratio of amylose to amylopectin contents, molecular structures of amylose and amylopectin, granule morphology, and minor-component contents. These structural features result in different gelatinization, pasting, retrogradation properties, and enzyme digestibility of starch granules. In this review, compositions and molecular structures of starches and their effects on the physicochemical properties are summarized and discussed.

• Journal of Microbiology and Biotechnology
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• 제4권4호
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• pp.364-366
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• 1994

Molecular properties of streptococcal nuclease purified from Streptococcus sp. were examined. The purified enzyme was stable in the range of pH 7 to 10 and easily inactivated above $60^{\circ}C$. Atomic spectroscopy analysis indicated that the enzyme contains Ca, Mg, Zn. Circular dichroism study showed 25% $\alpha$ -helix, 15% $\beta$-sheet and 30% $\beta$-tums.

• Bulletin of the Korean Chemical Society
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• 제1권1호
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• pp.10-17
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• 1980

Penicillin amidohydrolase was partially purified from the fermented broth of Bacillus megaterium, and was immobilized on nylon fiber. The surface area of nylon fiber was increased by roughening it with fine sand and activated by acid treatment. The free amino groups on the nylon fiber exposed by such treatment were then utilized to immobilize the penicillin amidase. Enzymatic properties of penicillin amidohydrolase immobilized on the nylon fiber by covalent bonding and cross linking with glutaraldehyde were studied and compared with those of soluble enzyme. The optimal pH and temperature profile of immobilized enzyme showed only slightly broader peaks, and the values of kinetic constants, $K_m$, $K_{ia}$, and $K_{ip}$, of the immobilized enzyme are only slightly greater than those of the soluble enzyme. These results suggest that the mass transfer effect on the reaction rate for the penicillin amidase immobilized on nylon fiber is not so significant as the enzyme immobilized on some other support material like bentonite. The experimental results of batch reaction agreed well with the results of computer simulation for both the immobilized and soluble enzyme systems, confirming the validity of the rate equation derived which was based on the combined double inhibition by two reaction products.

• Journal of the Korean Wood Science and Technology
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• 제27권4호
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• pp.65-71
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• 1999

This study was carried out to investigate the effect of xylanase pretreatment of the unbleached hardwood kraft pulp during the conventional Chlorine-Extraction- Hypochlorite (CEH) bleaching on pulp property. Optimum bleaching condition was evaluated by using Novozym produced from the fungus Humicola insolens. Also the effect of chelating agent prior to enzyme treatment was analyzed. The kappa number of enzymatic bleached pulp at the enzyme charge 10 IU/ml was slightly similar to that of bleached pulp without enzyme. By enzyme treatment, the chlorine charge in conventional CEH bleaching process of hardwood KP could be reduced by 17%, while no adverse effect on pulp yield and strength was. The optimum condition for enzyme pretreatment was 10 IU/ml xylanase charge, 3 to 4 hrs treatment, and 2% pulp consistency. In sugar composition in the enzyme pretreated pulp, arabinose and mannose were not much different, but more xylose was retained. This high content of hemicellulose in pulp seems to play an important role in pulp properties. The pulp pretreatment by chelating agent prior to enzyme treatment could improve the enzyme activity and enhance the bleaching effect at 0.2% diethylenetriamine pentaacetic acid (DTPA) charges.

• 펄프종이기술
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• 제31권1호
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• pp.23-30
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• 1999

The effects of polyelectrolytes and enzyme, alone and in combination, were investigated in OCC recycling system. Four types of the polyelectrolytes based on acrylamide, cationic and anionic monomers were applied to the enzyme-treated KOCC stock to improve the strength and drainage properties of testliner. The polyelectrolytes used in this work were designed in terms of molecular weight and charge density. The water conditions used for recycling were also varied. The results showed that the hydrolytic action of enzyme gave reduced surface area and amorphous region of fiber, and as a result, the cationic polymer was lost apparently its flocculating power due to the reduced bonding site of fiber surface. When the hardness and conductivity of water had been controlled to the conditins of OCC paper mill, the application of amphoteric polyelectrolyte to the enzyme-treated recycled stock was the most effective with respect to the strength and drainage properties of testliner.

• 한국염색가공학회지
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• 제14권1호
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• pp.18-26
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• 2002

Chitosan has reactive amino and hydroxyl groups which can be used to chemically alter its properties under the mild reaction conditions. Thus the cationization of Tencel with Chitosan is effective to modify the fabric. To investigate the modified properties of Tencel fabric, the tests were performed under the several finishing process with enzyme/glutaraldehyde/softener. The internal structure of Tencel which has the structure of cellulose II wasn't changed by enzyme, chitosan and crosslinking agent treatment and the thermal stability was improved by chitosan and crosslinking agent treatment. Wrinkle recovery angle under the dry condition increased highly until $0.1\textrm{mol}/\ell$ of glutaraldehyde concentration, and then decreased. Tensile strength of modified Tencel fabric decreased with increasing of weight loss, but it was improved more or less by chitosan, crosslinking agent and softener. Moisture regain was improved by enzyme and chitosan treatment. And antibacterial activity showed nearly 100% on Tencel fabric treated with 0.5% chitosan and adsorption of metal ion increased with increasing of chitosan concentration.

• Bulletin of the Korean Chemical Society
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• 제10권6호
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• pp.595-599
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• 1989

The effects of phosphatidic acid(PA) on the activity of phospholipase D were examined in detail. The enzyme activity was examined in the liposome system containing phosphatidylcholine and PA, which was suspended in a desired buffer solution by ultrasonication. The substrate of large unilamella vesicle (LUV) state by ultrasonication was more effective on the enzyme activity than that of multilamella vesicle(MLV) by water-bath type sonication. The most effective molar ratio of PC-PA liposome for enzyme activity was found to be 1:0.7. The other optimum conditions were found 5 mM $Ca^{2+}$ ion, pH 6.6, and incubation temperature of $27^{\circ}C. K_m \;and \;V_{max}$ values were estimated to be 1.43 mM and 0.8 $nmole/min/{\mu}g$ protein respectively. These properties in a PC-PA liposome system were compared with those in a PC-SDS mixed micelle system. The effects of other phospholipids and organic phosphates on the enzyme activity were also examined.

• 한국식품영양과학회지
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• 제19권5호
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• pp.429-433
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• 1990

Production and properties of invertase from. Aspergillus niger were investigated. Inuli and sucrose were best carbon source and yeast extract was most suitable for the production of the enzyme among tested carbon and nitrogen sources. The enzyme was maximally produced by cultivating the organism at medium of pH 4.5 and temperature of 3$0^{\circ}C$ The optimum pH and temperature for the enzyme activity were pH 5.0 and temperature of 5$0^{\circ}C$ respectively Among tested metal ions Hg2+ Cu2+ and Ag+ ions inhibited the enzyme activity drastically.

• 미생물학회지
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• 제17권2호
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• pp.58-64
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• 1979

Studies on some properties of cellulase isolated from Piricularia oryzae. Crude cellulases were prepared from dried rice plant powder (Tong-il, Pal-dal) culture of P. oryzae(N-2, C-8, T-2). The best yield of enzyme was obtained from the medium using Tong-il rice plant powder for P. oryzae cav. N-2 and 2%-sucrose concentration in preculture media. Two units of the enzyme were incubated at $60^{\circ}C$ for 1 hour with 1.0ml, 0.6% Na-CMC. The optimum temperature for the enzyme activity was at $60^{\circ}C$ and the optimum pH was at pH4.0. When Na-CMC was used as substrate the $K_m$ values of crude enzyme were calculated to be $1.05{\times}10^{-4}\;mM\;and\;V_{max}$ was 2.8 mmole/hour. A 10-fold partial purification was achieved by $(NH_4)_2SO_4$ precipitation followed by column chromatography on DEAE Sephadex A-25.

• 한국식품영양학회지
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• 제13권2호
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• pp.176-180
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• 2000

Microbial protease has been interesting due to the biological roles in the producing microorganism. A thermophilic Actinomyces produing protease was isolated from soil. The optimal medium composition and culture conditions for maximum protease production was as follows 0.5% soluble starch, 0.5% yeast extract. 0.1% K2HPO4, 0.05% CaCl2, initial pH 8.0 at 50$^{\circ}C$ for 48hours. The protease was purified by the procedure of ammonium sulfate precipitation, anion exchange chromatography(LC), DEAE high performance liquid chromatography and GPC HPLC. The purification fold of the purified enzyme was increased about 22.6. The optimal pH and temperature for reaction of the purified enzyme were 7.5 and 60$^{\circ}C$. The purified enzyme was stable for the pH range from 6.0 to 8.5, but was unstable when treated at 80$^{\circ}C$ for 10 minutes. The activity of the enzyme was inhibited by Ag+ and Cu2+.