• Polymer(Korea)
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• v.39 no.2
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• pp.300-310
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• 2015

In this study, we modified silica nanoparticles with N-[3-(trimethoxysilyl)propyl]ethylenediamine (TPED) silane coupling agent, which has one primary and one secondary amino groups in a molecule, to introduce amino groups on the silica surface. After modification of silica, we used 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) to introduce methacrylate groups by Michael addition reaction. We found about 30% of N-H groups on the TPED modified silica surface reacted with acrylate groups of AHM compared to about 85% of reaction between N-H groups of pure TPED with acrylate groups of pure AHM. This lower degree of Michael addition reaction for heterogeneous reaction between N-H groups on the solid TPED modified silica and liquid AHM compared to homogeneous reaction between pure liquid TPED and pure liquid AHM may be caused by lower mobility of grafted amino groups of TPED moiety and higher steric hindrance caused by solid silica particles.

• Journal of the Korean Wood Science and Technology
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• v.24 no.1
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• pp.48-53
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• 1996

Brown rot fungus, Tyromyces palustris, has been reported to cause the loss of strength accelerated by oxalate, a non-enzymatic low molecular weight acid, with minute weight loss of decaying wood in early stage. The production of oxalate in relation to wood decaying and the presence of oxaloacetase. an oxalate producing enzyme, were identified during the process. Tyromyces palustris produced the largest amount of oxalate among brown rot fungi. In order to find out the cleavage of pulp fiber, we submerged pulp fiber in oxalate solution and the results showed that the number of short pulp fiber was highly increased, compared with control solution. The pH of decaying wood was decreased to 1.77 which was close to that of saturated oxalate solution, pH 1.2, Thus, the oxalate was thought to be accumulated in the decaying wood, The oxaloacetase which accelerates production of oxalate was derived from fungus, and the production of oxalate by the enzyme was determined by using on UV/Vis spectrophotometer. Therefore, the oxalate was found to be produced by oxaloacetase during decay. The oxalate may cause the acid-hydrolysis of cellulose and hemicellulose. The oxalate was thought to reduce the degree of polymerization and increase the enzyme activity, which resulted in rapid loss of strength in early stage-an identical feature of brown rot fungus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.3
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• pp.233-241
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• 1988

In order to develop a new type of food source for the effective utilization of fish protein, plastein reaction was applied to improve the functional properties of sardine protein. Conditions necessary for optimal plastein productivity from sardine protein using pepsin, ${\alpha}-chymotrypsin$, protease(from Aspergillus saitoi) and papain were established. Sardine protein concentrate was hydrolyzed with pepsin yielding an approximate degree of hydrolysis of 78.4%. Enzyme induced plastein was optimized at : pH 4 for pepsin, pH 7 for ${\alpha}-chymotrypsin$, pH 5 for pretense and pH 6 for papain : Substrate concentrate 40% for pepsin and ${\alpha}-chymotrypsin$, 50% for pretense and papain : the time of incubation, 24hr : enzyme/substrate ratio, 1 : 100(w/v) incubation temperature, $50^{\circ}C$.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.3
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• pp.331-343
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• 1998

Sublethal dose of bacterial lipopolysaccharide (LPS) would induce protection against cardiac ischemic/reperfusion (I/R) injury. This study examines the following areas: 1) the temporal induction of the cardio-protection produced by LPS; and 2) the relations between a degree of protection and the myocardial prostacyclin ($PGI_2$) production. Rats were administered LPS (2 mg/kg, i.v.), and hearts were removed 1, 4, 8, 14, 24, 48, 72,and 96 h later. Using Langendorff apparatus, haemodynamic differences during 25 min of global ischemia/30 min reperfusion were investigated. The concentration of $PGI_2$ in aliquots of the coronary effluent was determined by radioimmunoassay as its stable hydrolysis product $6-keto-PGF1_{\alpha}$ and lactate dehydrogenase release were measured as an indicative of cellular injury. LPS-induced cardiac protection against I/R injury appeared 4 h after LPS treatment and remained until 96 h after treatment. $PGI_2$ release increased 2-3 fold at the beginning of reperfusion compared to basal level except in hearts treated with LPS for 48 and 72 h. In hearts removed 48 and 72 h after LPS treatment, basal $PGI_2$ was increased. To determine the enzymatic step in relation to LPS-induced basal $PGI_2$ production, we examined prostaglandin H synthase (PGHS) protein expression, a rate limiting enzyme of prostaglandin production, by using Western blot analysis. LPS increased PGHS protein expression in hearts at 24, 48, 72, 96 h after LPS treatment. Induction of PGHS expression appeared in both isotypes of PGHS, a constitutive PGHS-1 and an inducible PGHS-2. To identify the correlationship between $PGI_2$ production and the cardioprotective effect against I/R injury, indomethacin was administered in vivo or in vitro. Indomethacin did not inhibit LPS-induced cardioprotection, which was not affected by the duration of LPS treatment. Taken together, our results suggest that $PGI_2$ might not be the major endogenous mediator of LPS-induced cardioprotection.

• Applied Biological Chemistry
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• v.35 no.5
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• pp.339-345
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• 1992

In order to enhance the processing quality and utility of alaska-pollack meat, the optimum conditions for the preparation of pronase hydrolysate and the synthesis of plastein were investigated. The optimum temperature and pH for the hydrolysis of alaska-pollack by pronase were $40^{\circ}C$ and pH 7.0. The reaction time and enzyme concentration were 4 hr and 1,000 units per g of substrate. Under the above optimum conditions alaska-pollack was hydrolyzed by pronase yielding a hydrolytic degree of about 89%. Pronase hydrolysate was employed as substrate for plastein synthesis. The 30% pronase hydrolysates were adjusted to pH 7 for fruit-bromelain and pH 5 for stem-bromelain, and then plastein were synthesized by 1% bromelain at $40^{\circ}C$ for 24 hr. The plasteins synthesized by fruit- and stem-bromelain were consisted of peptides having average peptide length of 22.6 and 20.8 under the optimum synthetic conditions. The plastein synthesis reaction reduced considerably the bitterness of pronase hydrolysate.

• Polymer(Korea)
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• v.37 no.6
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• pp.777-783
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• 2013

We used dipodal type bis[3-(trimethoxysilyl)propyl]amine (BTMA) silane coupling agent to modify silica nanoparticles to introduce secondary amino groups on the silica surface. These grafted N-H groups were reacted with glycidyl methacrylate (GMA) to introduce polymerizable methacrylate groups on the silica surface. After modification reaction, we used several analytical techniques such as Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and solid state $^{13}C$ cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR) to analyze the effects of reaction time, reaction temperature and used GMA concentration on the modification degree between N-H groups on the silica surface and epoxide groups of GMA. We found increased introduction of methacrylate groups on the silica surface by ring opening reaction of epoxide groups of GMA with N-H groups on BTMA treated silica with increased reaction time, reaction temperature and used GMA concentration within our experimental conditions.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.745-750
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• 1998

Soybean isoflavones known as an anticarcinogenic factor were evaluated in some Korean soybean foods by high performance liquid chromatography. Unfermented soybean foods contained predominantly isoflavone ${\beta}-glycosides$ (genistin and daidzin), but in the fermented soybean foods isoflavones were present mainly as aglycones (genistein and daidzein). Average contents of isoflavones of tofu, soymilk and soy sprout were 1, 151, 676 and 424 mg/kg, respectively. Among the fermented soybean products, soybean paste (Chongkukjang) was highest in the isoflavone content (920 mg/kg) and the degree of hydrolysis of ${\beta}-glycosidic$ bonds was ranged from 30 to 100%. Doenjang, Chunjang and Kanjang contained lesser amounts of isoflavones and their contents were 627, 291 and 10 mg/kg, respectively. Korean traditional fermented foods, Chongkukjang and Doenjang could be regarded as the excellent sources of soy isoflavone aglycones.

• Food Science of Animal Resources
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• v.41 no.4
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• pp.687-700
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• 2021

This study performed to evaluate the applicability of functional dairy food materials by comparing the calcium solubilization ability and anti-inflammatory effects of hydrolyzed casein protein. Commercial enzyme (Alcalase^®; Neutrase^®; Protamex^®; Flavourzyme^®) was added to the 10% casein solution to prepare the casein hydrolysates. Samples obtained every hour [1:200 (w/v)]. According to results of measuring the degree of hydrolysis (DH), all of four enzymatic hydrolysates increased rapidly from 30 to 40 min, and after 150 min, there were no change. Protamex^® and Neutrase^® had the highest DH compared to others enzymatic hydrolysates. After that, peptides obtained throughout a preparative liquid chromatography system. In the calcium solubility experiments, neutrase fraction (NF) 4 and NF7 showed similar activities with casein phosphopeptide (CPP). In vitro cell experiments showed that no cytotoxicity except for NF6. Also, the production of nitric oxide (NO) inhibited as the concentration of fraction samples increased. The cytokine (IL-1α, IL-6, and TNF-α) production was lower than lipopolysaccharide (+) group significantly. Therefore, the possibility of anti-inflammatory activity found in the hydrolyzed samples. According to the above experiments, NF3 and Protamex Fraction (PF) 3 selected. Amino acids selected throughout an AccQ-Tag system. As a result, 17 species of amino acids and several species of unknown amino acids identified. Both fractions had the highest content of phenylalanine. This study identified the potential of biologically active and functional peptides derived from casein that affect the food and dairy industry.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2220-2231
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• 2018

Lipase from Candida rugosa was immobilized on $MgO{\cdot}SiO_2$ hybrid grafted with amine, thiol, cyano, phenyl, epoxy and carbonyl groups. The products were analyzed using Fourier transform infrared spectroscopy, nuclear magnetic resonance, low-temperature $N_2$ sorption and elemental analysis. Additionally, the degree of coverage of the oxide material surface with different functional groups and the number of surface functional groups were estimated. The Bradford method was used to determine the quantity of immobilized enzyme. The largest quantity of enzyme (25-28 mg/g) was immobilized on the hybrid functionalized with amine and carbonyl groups. On the basis of hydrolysis reaction of p-nitrophenyl palmitate to p-nitrophenol, it was determined how the catalytic activity of the obtained biocatalysts is affected by pH, temperature, storage time, and repeated reaction cycles. The best results for catalytic activity were obtained for the lipase immobilized on $MgO{\cdot}SiO_2$ hybrids with amine and carbonyl groups. The biocatalytic system demonstrated activity above 40% in the pH range 4-10 and in the temperature range $30-70^{\circ}C$. Lipase immobilized on the $MgO{\cdot}SiO_2$ systems with amine and epoxy groups retains, respectively, around 80% and 60% of its initial activity after 30 days of storage, and approximately 60-70% after 10 reaction cycles.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.1017-1027
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• 1995

This study was attempted to investigate physicochemical properties, molecular structural properties of native and acid-treated chestnut starch and chestnut starch gel. The amylose content was 18.9% and X-ray diffraction pattern showed Cb type. Swelling power was increased abruptly in the range of $65^{\circ}C{\sim}75^{\circ}C$ but increased slowly after that and solubility was increased abruptly until $70^{\circ}C$ but increased slowly after that. In amylograms which have different heating temperatures, cooling viscosity at $50^{\circ}C$ was reduced as heating temperature was increased. In molecular structural properties of amylose, ${\lambda}_{max}$ was 640 nm, ${\beta}-amylolysis$ limit was 84.2% and the degree of polymerization was 951 and in those of amylopectin, ${\lambda}_{max}$ was 570 nm, ${\beta}-amylolysis$ limit was 58.2%, the degree of polymerization was 1371 and average chain length was 22.6. In gel chromatography elution profiles of starch and amylose, 4.0% and 11.5% of low molecular weight-molecules($<5{\times}10^5$) were leached out. In gel chromatography elution profiles of soluble starch, the higher heating temperature was, the more high molecular weight-starches were leached out. The elution profiles after debranching amylopectin with pullulanase showed 2.2 of the ratio of peakIII(DP 10-15) to peakII(DP 35-45). Acid hydrolysis extent of 2.2 N HCI-treated starch at $35^{\circ}C$ for 10 days was 96% and hydrolysis rate showed two step pattern which had border line at 4 days. In elution profiles of acid treated chestnut starch, amylopectin peak was disappeared compeletly after 6 hrs and converted short chains of DP 10-15. Amylose content was increased until 6 hrs but decreased after that. Hardness of starch gel made at $75^{\circ}C$ of heating temperature and cohesiveness of starch gel made at $85^{\circ}C$ of heating temperature were the highest. Retrogradation rate of starch gels were relatively high, especially for the starch gel made at $75^{\circ}C$ of heating temperature.