• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.10
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• pp.1447-1452
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• 2011

Polyphenol oxidase (PPO) isoforms were partially purified from oyster mushroom (Pleurotus ostreatus) using various chromatography techniques, and their characteristics of heat stability, substrate affinity, optimum pH, and optimum temperature were investigated. Three PPO isoforms named PO-I, PO-II-1, and PO-II-2 were partially purified from oyster mushroom. The molecular weight of PO-II-1 was 70 kDa and PO-I and PO-II-2 were less than 6 kDa each. Characterization was carried out using a PPO isoform partially purified by hydrophobic interaction chromatography. Optimum temperature was $55^{\circ}C$ and optimum pH 5.0. However, the PPO was inactivated at neutral pH or by heating at $80^{\circ}C$ for 30 min, while the 40% PPO still remained active after heating at $60^{\circ}C$ for 45 min. The PPO isoform showed the highest substrate affinity to chlorogenic acid and pyrogallol, in which KM values were 1.01 and 2.06 mM, respectively. Therefore, these results suggested that the mushrooms should be stored at a pH higher than 7.0 and at a low temperature to prevent enzymatic browning.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.4
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• pp.659-664
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• 1996

The amount and characteristics of pectin in the albedo and flavedo layers of the citrus peels, and those of the pulp were investigated. Alcohol insoluble solid(AIS) content was the highest in albedo layer(18.1%), and the lowest in pulp(5.7%). The pulp and the albedo layer showed a potential pectin sources as containing pectins of 40.5% and 35.2% of the total polysaccharides of the pulp and the albedo layer, respectively. Total pectin contents were about 30% of the AIS and showed comparatively constant values among the byproducts. Hydrochloric acid soluble pectin contents were the hightest in the flavedo layer, 14.0%, and the lowest in the pulp, 4.4%. Over 90% of the total pectin could be extracted after 60min with 0.05N HCI at $85^{\circ}C.$ Microwave treatment reduced the extraction time significantly ; a comparable extraction yield was acquired after 10min with microwave treatment. The degree of esterification of the extracted pectin also increased with microwave treatment. Neutral sugars in the hydrolysate of the pectin were rhamnose, arabinose, galactose, glucose and xylose. No differences in molecular weight distribution of the pectin were found between the albedo and flavedo layers. Pectin of the pulp showed different molecular weight distribution from that of the peels.

• Biomedical Science Letters
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• v.6 no.3
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• pp.209-221
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• 2000

The purpose of this study was to investigate the practical availability of pretense production that can be used at home after isolating Serratia sp.2000-1 which produced extracellular pretense from clinical specimen. Basic production conditions and partial enzymatic characteristics of pretense produced by Serratia sp. 2000-1 was as follows: The kind and concentration of carbohydrate, nitrogen and metal salts for optimal enzyme production condition were each identified as the concentration of 1.5% glucose, 2.0% CSP, and 0.1% CaCl$_2$, and the optimal temperature, time and initial pH for culture were each 3$0^{\circ}C$, 72 hours, and pH 8.0. The final enzymatic yeild that was purified by 3 steps with ammonium sulfate precipitation (45~80%), DEAE-cellulose column chromatography, and Sephadex G-200 gel chromatography was 14.4%, and enzyme inactivity rate increased approximately 291314s. The optimal temperature and pH for purified pretense activity were 35$^{\circ}C$ and pH 7.0~8.0, and purified pretense activity was relatively stable by 4$0^{\circ}C$ at pH 6~10 for 30 min, however heating at 6$0^{\circ}C$ for 30 min, it liminated detectable pretense activity. The pretense activity was activated by $Mg^{2+}$, $Ba^{2+}$, $Ca^{2+}$, Mn$^{2+}$, but inactiviaed by Hg$^{2+}$, Ag$^{2+}$, Cu$^{2+}$, and the pretense activity was inhibited strongly by SDS among enzyme activity inhibitors. Further study is required to evaluate the practical availability of pretense production that can be used at home by isolating Serratia sp. from more clinical specimen and examining pretense more in details.

• Journal of Microbiology and Biotechnology
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• v.8 no.2
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• pp.171-177
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• 1998

The strain A49, which produces a new type of extracellular polysaccharide was isolated from soil samples. From morphological, physiological and biochemical tests, the strain A49 was identified as a Bacillus polymyxa and named Bacillus polymyxa A49. Bacillus polymyxa A49 was found to produce a highly viscous extracellular polysaccharide when grown aerobically in a medium containing glucose as the sole source of carbon. The polysaccharide (A49 POL) showed a homogeneous pattern on gel permeation chromatography (GPC) and its molecular weight was estimated to be about 1.6 mega dalton (mDa). The FT-IR spectrum of A49-POL revealed typical characteristics of polysaccharides. As a result of investigations with HPLC and carbozole assay, A49-POL was found to consist of L-fucose, D-galactose, D-glucose, D-mannose, and D-glucuronic acid, with the molar ratio of these sugars being approximately 1:2:7:50:12. Rheological analysis of A49 POL revealed that it is pseudoplastic and has a higher apparent viscosity at dilute concentrations than does xanthan gum. The consistancy factor of A49 POL was found to be higher, and the flow index of A49 POL lower, than xanthan gum. Its apparent viscosity was comparatively unstable at various temperatures. the A49 POL showed the highest apparent viscosity at pH 3. When salts were added to A49 POL solution, the solution was compatible with up to 10% KCl, 35% NaCl, 55% $CaCl_2$, 55% $MgCl_2$, 55% $K_2HPO_4$, and 110% $Ca({NO_3})_2$, respectively.

• The Korean Journal of Pharmacology
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• v.12 no.2 s.20
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• pp.33-41
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• 1976

Agkistrodon halys (Crotalidae) is the only species of poisonous snakes in Korea, and is divided into three subspecies; Agkistrodon bromhoffii brevicaudus, Agkistrodon calaginosus and Agkistrodon saxatilis. With the three venoms, the pharmacological actions on the cardiovascular system and intestine as well as some toxicological characteristics were studied. In addition, the precipitin test in an agar gel medium was employed for immunological comparison of the venoms and the sera of envenomed patients. The results obtained were as follows: Lyophilized venoms contained solids of $211{\sim}273mg/ml$, and LD50 to mice were 1.73 and 0.86 mg/kg in venoms of Agkistrodon bromhoffii brevicaudus obtained on July and October respectively, and 0.40 and 0.32 mg/kg in Agkistrodon calaginosus and the venoms of Agkistrodon saxatilis obtained on October was 2.29 mg/kg. Isoelectric focusing of lyophilized snake venoms showed 19 to 22 protein fractions and 2 to 3 isoamylase fractions. Acute irreversible hypotension was caused by the intravenous injection of large doses of venoms in rabbits and cats, but at the small doses, acute hypotension followed by slow recovery. Little changes of cardiac movements by the venom injection despite of marked hypotension were showed except bradycardia and arrhythmia prior the death. Also no changes on the isolated rabbit atria by the snake venoms were noted. The hypotensive effect of the snake venoms was prevented by the bilateral vagotomy or atropine pretreatment (1 mg/kg), but they did not affect when already the hypotension has undergone. In the isolated rabbit duodenum, small doses of venom increased the phasic movement, while large doses decreased after spastic contraction. With the injection of venoms in dog, strong contraction of gall-bladder was caused and it was not blocked by the pretreatment with phenoxybenzamine (10 mg/kg) or atropine (1.4 mg/kg). In the venoms of Agkistrodon bromhoffii brevicaudus and Agkistrodon calaginosus, at least 5 antigenic components were detected, and four of them were shared in common with each other. Polyvalent antivenin (Wyeth Lab. USA) had three common precipitating antibodies with the venom of Agkistrodon bromhoffii brevicaudus and Akistrodon calaginosus. In the serum of envenomed patients, no precipitating antibodies were seen to the venoms and little changes in serum protein, GOT and GPT were observed. In conclusion, the snake venoms obtained in Korea were highly toxic and caused chiefly the vascular collapse leading to death. This vascular collapse was resulted largely by cholinergic effects, and not cardiotoxin of venoms. In human, it is likely that precipitating antibodies to venom were not produced by an envenomed incidence to poisonous snakes.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.377-392
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• 2012

It has been known that small solid particles act as a stabilizer in pickering emulsion system. In this study, we successfully prepared stable pickering emulsion in n-hexylalcohol and water system with $TiO_2$ whose surface was treated by alkylsilane. The optimum condition to prepare pickering emulsion stabilized by $TiO_2$ particles was determined by amount of $TiO_2$ particles and ratio of water and oil phase. The type of pickering emulsion was dependent on wettability of particles for water and n-hexylalcohol. When the amount of $TiO_2$ particles increased up to 5.00 wt%, the stability of pickering emulsion was showed to be improved. The most stable pickering emulsion was prepared in the case of W/O type which has the ratio of oil and water phase (3 : 7). We tried to prepare porous $SiO_2-TiO_2$ composite pigments using a pickering emulsion as template at the optimal condition. Porous pigments were synthesized with Ludox HS-30 as an inorganic material by sol-gel process. The characteristics and shape of porous pigments were measured by optical microscope, SEM, BET, XRD and EDS.

• Journal of Applied Biological Chemistry
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• v.54 no.2
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• pp.94-100
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• 2011

A gene encoding a putative phospholipase D was isolated from Bacillus licheniformis and cloned into pGEM-T easy vector. The gene was expressed in E. coli BL21 (DE3) using a pET-21(a) vector containing His6 tag. Affinity purification of the recombinant phospholipase D with nickel-nitrilotriacetic acid (Ni-NTA) resin resulted major one-band by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The purified enzyme showed a molecular weight of 44 kDa. The optimum activity of enzyme was around pH 7.0 and the enzyme was also the most stable around this condition. The optimum temperature was about $40-45^{\circ}C$ and the enzyme still showed considerable activities at wide range of temperature. Among various detergents, Triton X-100 significantly increased the enzyme activity, resulting in 181% activity of control at 0.6 mM of the detergent. Calcium ion did not significantly affect the enzyme activity, suggesting that the enzyme might be classified into $Ca^{2+}$-independent PLD.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.999-1006
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• 2015

The endo-polygalacturonase gene (endo-pgaA) was cloned from DNA of Aspergillus niger SC323 using the cDNA synthesized by overlapping PCR, and successfully expressed in Saccharomyces cerevisiae EBY100 through fusing the α-factor signal peptide of yeast. The fulllength cDNA consists of 1,113 bp and encodes a protein of 370 amino acids with a calculated molecular mass of 38.8 kDa. After induction by galactose for 48 h, the activity of recombinant endo-PgaA in the culture supernatant can reach up to 1,448.48 U/mg. The recombinant protein was purified to homogeneity by ammonium sulfate precipitation and gel filtration column chromatography and subsequently characterized. The optimal pH and temperature of the purified recombinant enzyme were 5.0 and 50℃, respectively. The Michaelis-Menten constant (K_m) and maximal velocity (V_max) of the enzyme for pectin were 88.54 μmol/ml and 175.44 μmol/mg/min, respectively. The enzyme activity was enhanced by Ca²⁺, Cu²⁺, and Na⁺, and strongly inhibited by Pb²⁺ and Mn²⁺. The pectin hydrolysates were mainly galacturonic acid and other oligo-galacturonates. Therefore, these characteristics suggest that the recombinant endo-PgaA may be of potential use in the food and feed industries.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.71-76
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• 2008

Purpose: A simple and efficient method to prepare nanocrystalline ZnO thin film with pure strong UV emission on soda-lime-silica glass substrates by low-temperature annealing was improved. Methods: Crystal structural, surface morphological, and optical characteristics of nanocrystalline ZnO thin films deposited on soda-lime-silica glass substrates by prefiring final annealing process at 300$^{\circ}C$ were investigated by using X-ray diffraction analysis, field emission-scanning electron microscope, scanning probe microscope, ultraviolet-visible-near infrared spectrophotometer, and photoluminescence. Results: Highly c-axis-oriented ZnO films were obtained by prefiring at 300$^{\circ}C$. A high transmittance in the visible spectra range and clear absorption edge in the ultra violet range of the film was observed. The PL spectrum of ZnO thin film with a deep near band edge emission was observed while the defect-related broad green emission was nearly quenched. Conclusions: Our work will be possibly adopted to cheaply and easily fabricate ZnO-based optoelectronic devices at low temperature, below 300$^{\circ}C$, in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.2
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• pp.71-79
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• 1988

For the purpose of producing low salt fermented anchovy by accelerated method with a strong proteolytic bacteria, in this study, a strong proteolytic bacterium was isolated from low salt fermented anchovy and its bacteriological characteristics and properties of protease were experimented. The results obtained were as fellows : three proteolytic bacteria, Aeromonas anaerogenes Barillus subtilis and Staphylococcus saprophyticus were isolated from low salt fermented anchovy($4\%\;of\;salt,\;4\%\;of\;KCl,\;0.5\%\;of\;lactic\;acid,\;6\%$of sorbitol and $4\%$ of alcohol extract of red pepper) after 40 days fermentation. Among these strains, which grow best at $30^{\circ}C$, pH 7.0, B. subtilis was found the best proteolytic strain and benefit for industrial use as shown $0.95\;hr^{-1}$ of specific growth rate, $89{\mu}g-Tyr/hr.ml$ of maximum activity after 12 hrs culture in TPY broth. The protease produced by by B. subtilis showed maximum activity at $35^{\circ}C$, pH 7.0, and molecular weight was estimated to be 23,000 by Sephadex G-100 filtration, and it was supposed to be a kind of metal chelator sensitive neutral protease from the results of strong sensitivity against EDTA, o-phenanthroline and metal ions such as $Cu^{2+},\;Ni^{2+},\;Fe^{2+}.Km$ value of that by method of Lineweaver-Burk was determinded to be $0.73\%$ for casein as a substrate.