• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.370-378
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• 2000

The composite restorative resins have their insufficient resistance to wear. The subsurface degradation within the restoration is considered to be associated with wear. The aim of this study was to evaluate the resistance to degradation of six commercial composite resins in an alkaline solution. The brands studied were Clearfil APX(Kuraray), Heliomolar(Vivadent), Surefil(Dentsply), TPH(Dentsply), Tetric Ceram(Vivadent), and Z100(3M). Preweighed discs of each brand were exposed 0.1N NaOH solution at $60^{\circ}C$. After 14 days they were removed, neutralized with HCL, washed with water and dried to constant mass at $60^{\circ}C$. Resistance to degradation was evaluated on the basis of the following parameters: (a) mass loss(%) - determined from pre-and post-exposure specimen weights; (b) Si loss (ppm)-obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation depth$({\mu}m)$ - measured microscopically (SEM) from polished circular sections of exposed specimens. The results were as follows: 1. The mass loss was in descending order by Z100, TC H, S, CL, TPH and in the range of $0.45\sim3.64%$ 2. The degradation layer depth was in descending order by H, Z100, S, TC, TPH, CL and in the range of $10.85\sim73.38{\mu}m$ 3. For the Si concentration, Z100 was the highest of all 4. The highly significant correlation(r=0.81, p<0.05) was observed between mass loss and degradation depth. 5. Under scanning electronmicroscopy, the degradation of connection between resin matrix and fillers was observed 2 weeks after soaking in NaOH solution.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.81-88
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• 1990

For the selection of powerful antagonistic bacterium for biological control of soilborne Fusarium solani causing root rot of many important crops, the best YPL-1 strain was selected among 300 strains of bacteria isolated from rhizosphere in ginseng root rot-suppressive soil. The strain was identified to be a species to Pseudomonas stutzeri. With in vitro fungal inhibition tests, antagonistic substance of P. stutzeri YPL-1 against F. solani was presumed to be heat unstable, macromolecular substances such as protein. Also, it was shown that antifungal activity of P. stutzeri YPL-1 increased in proportion to its chitinase production. P. stutzeri YPL-M122 (chi-, lam -) which was deprived of the productivity of chitinase and laminarinase by NTG mutagenesis had lost antifungal activity, completely. And P. stutzeri YPL-MI53 (chi-) had only 4.1% of its antifungal activity. P. stutzeri YPL-1 was not able to produce any extracellular siderophore in iron-deficent minimal medium. It is confident that the antifungal mechanism of P. stutzeri YPL-1 for biocontrol of F. solani depends on lysis rather than antibiosis :the mechanism of lysis appears to involve enzymatic degradation of the cell will components of F. solani by hydrolytic enzymes of more chitinase and less laminarinase.

• Journal of Microbiology
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• v.43 no.3
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• pp.285-294
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• 2005

A bacterial strain M4-7 capable of degrading various polyesters, such as poly$(\varepsilon-caprolactone)$, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxyoctanoate), and poly(3-hydroxy-5-phenylvalerate), was isolated from a marine environment and identified as Pseudomonas alcaligenes. The relative molecular mass of a purified extracellular medium-chain-length poly(3-hydroxyalkanoate) (MCL-PHA) depolymerase $(PhaZ_{palM4-7})$ from P. alcaligenes M4-7 was 28.0 kDa, as determined by SDS-PAGE. The $PhaZ_{palM4-7}$ was most active in 50 mM glycine-NaOH buffer (pH 9.0) at $35^{\circ}C$. It was insensitive to dithiothreitol, sodium azide, and iodoacetamide, but susceptible to p-hydroxymercuribenzoic acid, N-bromosuccinimide, acetic anhydride, EDTA, diisopropyl fluorophosphate, phenylmethylsulfonyl fluoride, Tween 80, and Triton X-100. In this study, the genes encoding MCL-PHA depolymerase were cloned, sequenced, and characterized from a soil bacterium, P. alcaligenes LB19 (Kim et al., 2002, Biomacro-molecules 3, 291-296) as well as P. alcaligenes M4-7. The structural gene $(phaZ_{palLB19})$ of MCL-PHA depolymerase of P. alcaligenes LB19 consisted of an 837 bp open reading frame (ORF) encoding a protein of 278 amino acids with a deduced $M_r$ of 30,188 Da. However, the MCL-PHA depolymerase gene $(phaZ_{palM4-7})$ of P. alcaligenes M4-7 was composed of an 834 bp ORF encoding a protein of 277 amino acids with a deduced Mr of 30,323 Da. Amino acid sequence analyses showed that, in the two different polypeptides, a substrate-binding domain and a catalytic domain are located in the N-terminus and in the C-terminus, respectively. The $PhaZ_{palLB19}$ and the $PhaZ_{palM4-7}$ commonly share the lipase box, GISSG, in their catalytic domains, and utilize $^{111}Asn$ and $^{110}Ser$ residues, respectively, as oxyanions that play an important role in transition-state stabilization of hydrolytic reactions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.293-299
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• 2020

This study was undertaken to optimize combining the processes of enzymatic hydrolysis and extraction for lycopene production from autumn olive berry. The autumn olive berry was pulverized and suspended in water, followed by treatment with various hydrolytic enzymes including Ceremix, Celluclast, AMG, Viscozyme, Pectinex, Promozyme, Ultraflo and Tunicase. Reaction solutions were subjected to extraction by applying different organic solvents including acetone, ethyl acetate, hexane and chloroform. Highest yields of lycopene extraction were obtained with the Ceremix (hydrolysis enzyme) and chloroform (extraction solvent) combination. Subsequently, using this ideal combination, enzymatic hydrolysis conditions, including enzyme concentration, pH and temperature, were statistically optimized to 0.58%, 5.5 and 54.4℃, respectively, by applying the response surface method. The lycopene extraction yield increased 2.3-fold (22.6 mg/100g) by using the selected combined process. We propose that these results could be used for the future development of bioactive materials required for bio-health care products.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.10-19
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• 1986

A study on the rapid fermentation of fish sauce has been carried out for effective utilization of sardine. The frozen sardine was thawed at room temperature, chopped, homogenized with equal amount of water and then hydrolyzed by addition of commercial proteolytic enzymes such as bromelain, papaya protease, ficin and a enzyme mixture under different conditions of hydrolysis. The effect of wheat gluten for masking fishy odor and color development during thermal treatment were also tested. The reaction mixture was heated for 30 minutes at $100^{\circ}C$ for enzyme inactivation, pasteurization and color development and then centrifuged for 20 minutes at 4,000 rpm. Finally, table salt and benzoic acid were added for bacteriostatic effect. The results were summarized as follows ; 1. The hydrolyzing temperature, time, pH and the concentration of enzymes based on the weight of whole sardine for optimal hydrolysis were as follows: autolysis, $52.5^{\circ}C$, 4 hours, pH 8.0: with $0.25\%$ bromelain, $52.5^{\circ}C$, 4 hours, pH 6.6 :with $0.25\%$ ficin, $52.5^{\circ}C$, 4 hours, pH 6.8: with $0.3\%$ papaya protease, $52.5^{\circ}C$, 4 hours, pH 6.6: with $6\%$ enzyme mixture, $52.5^{\circ}C$, 4 hours, pH 6.9, respectively. But pH control was not much beneficial in increasing yield. 2. The hydrolytic reaction of chopped sardine with proteolytic enzymes could be interpreted as a first order reaction that devided into 2 periods with different reaction rate constsnts. $Q_{10}$ values of the first period prior to 4 hours were 1.23 to 1.31, and those of post 4 hours were 1.25 to 1.55. The corresponding activation energies were $1.81{\times}10^4\;to\;2.34{\times}10^4\;kJ/kmol$ and $1.92{\times}10^4\;to\;3.77{\times}10^4\;kJ/kmol$, respectively. 3. The reasonable amount of $75\%$ vital wheat gluten for addition was $9\%$ of chopped sardine. 4. The dark brown color was mainly developed during the thermal treatment for 30 minutes at $100^{\circ}C$ and not changed during storage.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1295-1300
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• 2009

A 2,172-bp full-length gene (aga-F78), encoding a protease-resistant $\alpha$-galactosidase, was cloned from Rhizopus sp. F78 and expressed in Escherichia coli. The deduced amino acid sequence shared highest identity (45.0%) with an $\alpha$-galactosidase of glycoside hydrolase family 36 from Absidia corymbifera. After one-step purification with a Ni-NTA chelating column, the recombinant Aga-F78 migrated as a single band of ~82 and ~210 kDa on SDS-PAGE and nondenaturing gradient PAGE, respectively, indicating that the native structure of the recombinant Aga-F78 was a trimer. Exhibiting the similar properties as the authentic protein, purified recombinant Aga-F78 was optimally active at $50^{\circ}C$ and pH 4.8, highly pH stable over the pH range 5.0-10.0, more resistant to some cations and proteases, and had wide substrate specificity (pNPG, melidiose, raffinose, and stachyose). The recombinant enzyme also showed good hydrolytic ability to soybean meal, releasing galactose of $415.58\;{\mu}g/g$ soybean meal. When combined with trypsin, the enzyme retained over 90% degradability to soybean meal. These favorable properties make Aga-F78 a potential candidate for applications in the food and feed industries.

• Journal of Life Science
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• v.29 no.12
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• pp.1408-1414
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• 2019

Enzymes are widely used in industrial applications such as detergents, food, feed production, pharmaceuticals and medical applications and major contributors to clean industrial products and processes. To screen, identify, and characterize the enzymes the zymography techniques are routinely used. The zymography technique is a simple, sensitive, and quantifiable technique that is widely used to detect functional enzymes following electrophoretic separation in sodium dodecyl sulfate (SDS)-polyacrylamide gels. The method is a versatile two-stage technique involving protein separation by electrophoresis followed by the detection of enzyme activity in polyacrylamide gels under non-reducing conditions. It is based on SDS-polyacrylamide gel (PAG) copolymerization with substrates, which are degraded by the hydrolytic enzymes restored in enzyme reaction buffer after the electrophoretic separation. Any kind of biological sample can be applied and analyzed on zymography, including culture supernatants of microbes, plants extracts, blood, tissue culture fluids, enzymes in foods extracts and metaproteome. The advantage of zymography is that it is possible to directly detect the protein with activity on the electrophoretic gel as well as confirm the activity at the nanogram level. Thus, this zymography technology can be applied in various fields. However, these advantages are rather disadvantageous and can often lead to experimental errors. In this review, the advantages, disadvantages, and problem solving of zymography technique are described.

• Applied Biological Chemistry
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• v.40 no.2
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• pp.95-100
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• 1997

This study was aimed to survey inexpensive and reliable sources of chitinase from the animal origin. The stomach and its content of the broiler, the cod, the yellowtail and ${\beta}-glucuronidase$ from snail gut showed a considerable chitinolytic activity, while those of the bas didn't have any detectable activity. These crude enzymes was found to have both endo- and exochitinase activity. The effects of pH and temperature on the enzyme activity were variable. The hydrolytic products of colloidal chitin by the enzyme preparation from the broiler and the cod were chitooligomers having the degree of polymerization between 3 and 5. Furthermore we observed the chitosanolytic activity from these enzymes. In the degradation of chitosan the chyme of the broiler had the highest activity and ${\beta}-glucuronidase$ from snail gut followed. On the basis of the fact that the by-product of the broiler was not only commercially available but also the most potent in the endochitinase activity and the lowest in the exochitinase activity, we conclude that the gizzard and its chyme are considered as the most suitable source of the industrial chitinase among animals studied in this paper.

• Applied Biological Chemistry
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• v.39 no.2
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• pp.140-146
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• 1996

Imidacloprid and a series of the related compounds were synthesized, and influence of 3-N substituents(R) on the insecticidal activities against Brown plant hopper(Nilaparvata lugens) and Green peach aphid(Myzus persicae) were examined quantitatively from the structure-activities relationships(Shh) techniques. The results indicated that the molecular hydrophobicity$({\pi})$ and inductive substituent constant$({\sigma}^{\ast})$ of substituents(R) at 3-nitrogen position on the imidazolidine ring were important factors. Variations in the potency were parabolically related to the both constants. In case of Brown plant hopper, optimum value of ${\pi}$ constant was 0.52, whereas the value of ${\sigma}^{\ast}$ constant against Green peach aphid was 1.17, respectively. Among them, the strong electron withdrawing groups$({\sigma}^{\ast}>0)$ such as methyl and benzenesulfonyl group(7 & 8) showed lower insecticidal activity and non-substituted, 1(imidacloprid) showed the best insecticidal activity. It seems that the intramolecular associated(H-bond) form between 2-N-nitro group and 3-imid group may contribute to the higher insecticidal activity to the both sucking insects. And in aqueous solution, 1 showed higher residual activity below pH 6.0, and the half-life$(T_{1/2})$ was about 6 month at pH 7.0 $(ca.\;k_{obs.}:5{\times}10^{-8}sec.^{-1})$ and $45^{\circ}C$.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.611-620
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• 2007

Statement of problem: Second-generation indirect composite resins have been improved flexural strength, compressive strength, hydrolytic degradation resistance, wear resistance compared to first-generation indirect composite resins, but there are still some problems as hydrolysis and low wear resistance. Some manufacturers claim that wear resistance of their materials has been improved, but little independent study has been published on wear properties of these materials and the properties specified in the advertising materials are largely derived from in-house or contracted testing. Purpose: This study was to evaluate the wear of indirect composite resins (SR Adore, Sinfony, Tescera ATL) and gold alloy against the human enamel. Material and method: Extracted human incisors and premolars were sectioned to $2{\times}2{\times}2mm$ cube and embedded in the clear resin and formed conical shaped antagonist to fit the jig of pin-on-disk tribometer. Total 20 antagonists were stored in distilled water. Five disk samples, 24mm in diameter and 1.5mm thick, were made for each of three groups of indirect composite resins and gold alloy group, and polished to #2,000 SiC paper on auto-polishing machine. Disk specimens were tested for wear against enamel antagonists. Wear test were conducted in distilled water using a pin-on-disk tribometer under condition (sliding speed 200rpm contact load 24N, sliding distance 160m). The wear of the enamel was determined by weighing the enamel antagonist before and after test, and the weight was converted to volumes by average density. The wear tracks were analyzed by scanning electron microscopy and surface profilometer to elucidate the wear mechanisms. Statistical analysis of the enamel wear volume, wear track depth and wear tract width of disk specimens were accomplished with one-way ANOVA and the means were compared for significant differences with Scheffe's test. Results: 1. The enamel wear was most in gold alloy, but there were no statistically significant differences among all the groups (P>.05). 2. In indirect composite resin groups, the group to make the most shallow depth of wear tract was Sinfony, followed by Tescera ATL, SR Adoro (P<.05). Gold alloy was shallower than Sinfony, but there was no statistically significant difference between Sinfony and gold alloy (P>.05). 3. The width of wear tract of SR Adore was larger than the other groups (P<.05), and there were no statistically significant differences among the other groups (P>.05). 4. SEM analysis revealed that Sinfony and gold alloy showed less wear scars after test, Tescera ATL showed more wear scars and SR Adore showed the most. Conclusion: Within the limits of this study, Sinfony and gold alloy showed the least wear rates and showed similar wear patterns.