• Journal of Microbiology and Biotechnology
• /
• 제7권5호
• /
• pp.310-317
• /
• 1997

Enzymatic synthesis of glucosyl-sugar alcohols using various transglycosylating enzymes, such as cyclodextrin glucanotransferase (CGTase), ${\alpha}$-amylase, ${\alpha}$-glucosidase, and pullulanase was investigated using various sugar alcohols, such as sorbitol, xylitol, inositol, maltitol, and lactitol as glucosyl acceptors. CGTase showed the highest transglycosylating activity to sugar alcohols compared to other transglycosylating enzymes, and inositol and maltitol were the most suitable glucosyl acceptors. Soluble starch, extruded starch, cyclodextrins, and maltooligosaccharides were also identified to be adequate glucosyl donors for transglycosylation reaction of CGTase to sugar alcohols. The synthesis of glucosyl-maltitol in the reaction system using extruded starch as the glucosyl donor and maltitol as the glucosyl acceptor showed the best results showing the highest transglycosylation yield. The transglycosylation products were purified by activated carbon column chromatography with ethanol gradient elution. Chemical structures of above transglucosylated products were analyzed by nuclear magnetic resonance spectroscopy, and two products were identified to be maltotritol and maltotetraitol, in which one or two glucose molecules attached to the parent maltitol molecule by a ${\alpha}$-l,4-glucosidic bond, respectively.

• 한국세라믹학회지
• /
• 제29권12호
• /
• pp.942-948
• /
• 1992

Ultrafine iron oxide powder, {{{{ gamma }}-Fe2O3 and $\alpha$-Fe2O3, were prepared by the thermal decomposition of organometallic compounds. The formation process of powder includes the thermal decomposition and oxidation of the organometallic precursors, Fe(N2H3COO)2(N2H4)2 (A) and N2H5Fe(N2H3COO)3.H2O (B). The organometallic precursors, A and B, were synthesized by the reaction of ferrous ion with hydrazinocarboxylic acid, and characterized by quantitative analysis and infrared spectroscopy. The mechanistic study for the thermal decomposition was performed by DAT-TG. The iron oxide powder was obtained by the heat treatment of the precursors at 20$0^{\circ}C$ and $600^{\circ}C$ for half an hour in air. The phases of the resulting product were proved {{{{ gamma }}-Fe2O3 and $\alpha$-Fe2O3 respectively. The particle shape was equiaxial and the particle size was less than 0.1 ${\mu}{\textrm}{m}$. Magnetic properties of the {{{{ gamma }}-Fe2O3 powder obtained from A and B was 234 Oe of coercivity, 64.26 emu/g of saturation magnetization, 23.59 emu/g of remanent magnetization and 24.1 Oe, 47.27 emu/g, 3.118 emu/g respectively. The value of $\alpha$-Fe2O3 powder was 1.494 Oe, 0.4862 emu/g, 0.1832 emu/g and 1,276 Oe, 0.4854 emu/g, 0.1856 emu/g respectively.

• 센서학회지
• /
• 제13권4호
• /
• pp.282-286
• /
• 2004

${\alpha}-Fe_{2}O_{3}$ films were prepared by ultrasonic spray pyrolysis (USP) on $SiO_{2}$ coated Si wafers using iron acetylacetonate as an iron precursor. The crystallographic properties and surface morphologies of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray photoelectron spectroscopy (XPS) was carried out to determine the Fe oxidation states. In order to observe stability of the films to temperature, the resistance variation of the films with an ambient temperature was measured. The effects of substrate temperature on the structural and electrical properties of the ${\alpha}-Fe_{2}O_{3}$ films were studied. The films were densified from the substrate temperature of $350^{\circ}C$. The grain size of the films grown at $400^{\circ}C$ was shown to be increased abruptly comparing with that of $350^{\circ}C$. The films showed a low resistance variation between the ambient temperature of $300^{\circ}C$ and $350^{\circ}C$.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제3권2호
• /
• pp.61-66
• /
• 1998

Glycolipids produced by Pseudomonas aeruginosa YPJ-80 were characterized by chromatographic and spectorscopic techniques as a mixture of two rhamnolipids. For recovery of glycolipids from the culture broth, various isolation methods including ultrafiltration, adsorption and solvent extraction were compared. Ultrafiltration showed the best results in terms of glycolipids recovery. Further purification for spectroscopic analysis was carried out by adsorption chromatography and preparative thin layer chromatography. From the spectroscopic analysis, such as IR spectroscopy. FAB-MS, 1H-NMR and 13C-NMR and hydrolysis analysis, the glycolipids were identified as L-${\alpha}$-rhamnopyranosyl-${\beta}$-hydroxydecanoly-${\beta}$-hydroxydecanoate and 2-O-${\alpha}$-L-rhamnopyranosyl-${\alpha}$-L-rhamnopyranosyl-${\beta}$-hydroxydecanoyl-${\beta}$-hydroxydecanoate. Monorhamnolipid and dirhamnolipid lowered the surface tension of water to 28.1 mN/M and 29.3 mN/m, respectively.

• Journal of Microbiology and Biotechnology
• /
• 제28권8호
• /
• pp.1299-1309
• /
• 2018

We previously reported on lactophoricin (LPcin), a cationic ${\alpha}-helical$ antimicrobial peptide derived from bovine milk, which has antimicrobial effects on Candida albicans as well as Gram-positive and Gram-negative bacteria. In this study, we designed the LPcin-YK3 peptide, a shorter analog of LPcin, and investigated its antimicrobial activity. This peptide, consisting of 15 amino acids with + 3 net charges, was an effective antimicrobial agent against the on the Gram-positive strain, Staphylococcus aureus (MIC: $0.62{\mu}g/ml$). In addition, the hemolytic activity assay revealed that the peptide was not toxic to mouse and human erythrocytes up to $40{\mu}g/ml$. We also used circular dichroism spectroscopy to confirm that peptide in the presence of lipid has ${\alpha}-helical$ structures and later provide an overview of the relationship between each structure and antimicrobial activity. This peptide is a member of a new class of antimicrobial agents that could potentially overcome the problem of bacterial resistance caused by overuse of conventional antibiotics. Therefore, it could be used as a therapeutic or natural additive, particularly in the cosmetics industry.

• Bulletin of the Korean Chemical Society
• /
• 제22권8호
• /
• pp.837-841
• /
• 2001

The electronic absorption and Raman spectra of $\alpha\omega-diphenylpolyenyl$, anions Ph(CH)nPh- (DPn- , n = 3, 5, 7, 9, and 13), with odd number of carbons at the polyene part, have been studied in the tetrahydrofuran (THF) solutions and in their solid film states, respectively. In the case of Raman spectra for DPn- , the frequencies and relative intensities of some Raman peaks regularly change with the increase of polyene chain length. The spectral patterns of anions (DPn- ) are very similar with those of radical anion (DPn${\cdot}$- ). However, the C=C stretching peaks of DPn- anions are observed in the 25-35 cm-1 higher frequency region than those of DPn${\cdot}$- radical anions. In the case of long chain models such as DP9- and DP13- , the C=C stretching peaks are observed in even higher frequency region than those of the corresponding neutral polyenes such as DP8, DP10, and DP12. The Raman patterns of DPn- anions in the THF solutions are similar with those in their solid film states. On the other hand, their electronic absorption spectra show a considerable difference each other. The n- ${\pi}*$ electronic absorption bands of DPn- anions in the THF solutions have been observed in the 0.27-0.39 eV lower energy region than those in their solid film states due to the solvent effects on polyene anions.

• Journal of Magnetics
• /
• 제16권1호
• /
• pp.23-26
• /
• 2011

The effects of titanium ions on the crystallographic and spin-rotation transitions in iron sulfide have been examined by M$\"{o}$ssbauer spectroscopy in the temperature range of 78 to 600 K. It is noted that the titanium impurity of $Ti_{0.02}Fe_{0.98}S$ affects both the crystallographic and spin-rotation transitions of the iron sulfide. 2% impurity of $Ti^{2+}$ in FeS causes the increase in the difference between the spin rotation and ${\alpha}$ transition temperature by as much as 10 K compared with that for FeS. Both 1c and 2c structures coexist in the range between the ${\alpha}$ transition temperature and approximately 26 K, with a smaller hyperfine field corresponding to the 1c structure. The spin-rotation temperature for $Ti_{0.02}Fe_{0.98}S$ was measured to be 365 K, which is 10 K lower than the ${\alpha}$ transition temperature. By the 2% impurity of $Ti^{2+}$ in FeS the N$\'{e}$el temperature appreciably is not affected.

• Natural Product Sciences
• /
• 제24권4호
• /
• pp.272-283
• /
• 2018

The root-knot nematode, Meloidogyne incognita caused a serious damage to many plants. The phenolic components of the leaves of Schinus terebinthifolius were investigated as potential nematicidal agents for M. incognita. Nine compounds were isolated and characterized as viz., 1,2,3,4,6-pentagalloyl glucose (1), kaempferol-3-O-${\alpha}$-L-rhamnoside (Afzelin) (2), quercetin-3-O-${\alpha}$-L-rhamnoside (Quercetrin) (3), myricetin (4), myricetin-3-O-${\alpha}$-L-rhamnoside (Myricetrin) (5), methylgallate (6), protocatechuic acid (7), quercetin (8), and gallic acid (9) using nuclear magnetic resonance (NMR) spectroscopy. Compound 1 showed pronounced nematicidal activity compared to Oxamyl as a positive control. It showed the lowest eggs-hatchability (34%) and the highest mortality in nematode population (21% after 72 hours of treatment) at a concentration of $200{\mu}g/mL$. It exhibited the best suppressed total nematode population, root galling and number of eggmasses in infected tomato plants. The total carbohydrates and proteins were also significantly induced by 1 with reduction in total phenolics and increase in defense-related proteins. Thus, compound 1 could be a promising, more safe and effective natural nematicidal agent for the control of root-knot nematodes.

• Food Science and Biotechnology
• /
• 제17권2호
• /
• pp.302-307
• /
• 2008

Novel amylase inhibitors were synthesized via transglycosylation by Thermotoga maritima glucosidase (TMG). TMG hydrolyzes acarbose, acarviosine-glucose, and maltooligosaccharide by releasing $^{14}C$-labeled glucose from the reducing end of each molecule. When TMG was incubated with acarviosine-glucose (the donor) and glucose (the acceptor), two major transfer products, compounds 1 and 2, were formed via transglycosylation. The structures of the transfer products were determined using thin-layer chromatography (TLC), high-performance ion chromatography (HPIC), and $^{13}C$ nuclear magnetic resonance (NMR) spectroscopy. The results indicate that acarviosine was transferred to glucose at either C-6, to give a $\alpha-(1{\rightarrow}6$) glycosidic linkage, or at C-3, to produce an $\alpha-(1{\rightarrow}3$) glycosidic linkage. The transfer products showed a mixed-type inhibition against porcine pancreatic $\alpha$-amylase; therefore, they may be useful not only as inhibitors but also as acarbose transition-state analogs to study the mechanism of amylase inhibition.

• 한국응용과학기술학회지
• /
• 제30권2호
• /
• pp.251-257
• /
• 2013

Methotrexate의 영향은 혼탁매질에서 형광체, 산란체와 응흡수체에 의해 파장과 산란된 형광 세기로 규명되는데, laser induced fluorescence(LIF) 분광학에 의해 분자특성으로 나타난다. 산란매질에서 광학적 효과는 광학적 파라미터들((${\mu}_s$, ${\mu}_a$, ${\mu}_t$)에 의해 표현되고 응집은 고-액상 분리공정에서 중요하게 활용되고 있다. 따라서 입자가 서로 접근될 때 콜로이드 입자들의 상호작용을 LIF와 응집효과로 분석하였다. 산란계수는 산란매질, L-${\alpha}$-Phosphatidylcholine의 농도가 증가함에 따라 산란 광학적 파라미터가 증가하였으나 흡수 파라미터는 감소하였다. 광학적 파라미터들은 레이저 광원에서 검출기까지 깊이의 함수에 의해 깊이가 깊어짐에 따라 산란세기가 기하급수적으로 감소함을 알 수 있다. 이는 유지화학, 생의학 생성물, 레이저 의학, 의공학 분야적용에 LIF와 입자이동 현상은 아주 적합한 모델 연구에 큰 도움이 될 것이다.