• Journal of Applied Biological Chemistry
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• 제44권3호
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• pp.125-130
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• 2001

A putative protein encoded by Arabidopsis AtMTN3 gene, a homologue of Medicago truncatula MTN3, consists of 285 amino acid residues, and has a predicted molecular mass of 31.5 kDa and a calculated pI of 9.1. Primary amino acid sequence analyses have revealed that the protein contains seven putative transmembrane regions with N-terminus oriented to the outside of the membrane. The AtMTN3 protein shows overall 16.4% of amino acid identity with the rat GALR3 protein, known to be a G-protein-coupled receptor. The gene is present as a single copy in the Arabidopsis genome, and expressed in aerial parts but not in roots of Arabidopsis. Therefore, AtMTN3 appears not to be specifically involved in Rhizobium-induced nodule development, as was predicted for the MTN3 gene. These proteins possibly mediate signal transmission through G-protein-coupled pathways during general interactions between plants and symbiotic or pathogenic microbes.

• 한국자기공명학회논문지
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• 제4권1호
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• pp.41-49
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• 2000

To design more efficient peptide antagonist against the HBV, preSl(21-47) which carries the HBV receptor binding site for hepatocytes was synthesized and the solution structure of preSl(21-47) was investigated using CD spectroscopy and NMR spectroscopy in membrane-mimicking environments. According to CD spectra, preSl(21-47) has a random structure in aqueous solution, while conformational change was induced by addition of TFE and SDS micelle. Tertiary structures as determined by NMR spectroscopy shows that preSl(21-47) has a very flexible structure even in SDS micelle.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.2039-2044
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• 2011

A semi-continuous and automated method for quantifying atmospheric ammonia at the parts per billion level has been developed. The instrument consists of a high efficiency diffusion scrubber, an electrolytic on-line anion exchange device, and a conductivity detector. Water soluble gases in sampled air diffuse through the porous membrane and are absorbed in an absorbing solution. Interferences are eliminated by using an anion exchange devises. The electrical conductivity of the solution is measured without chromatographic separation. The collection efficiency was over 99%. Over the 0-200 ppbv concentration range, the calibration was linear with $r^2$ = 0.99. The lower limit of detection was 0.09 ppbv. A parallel analysis of Seoul air over several days using this method and a diffusion scrubber coupled to an ion chromatography system showed acceptable agreement, $r^2$ = 0.940 (n = 686). This method can be applied for ambient air monitoring of ammonia.

• 공업화학
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• 제5권6호
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• pp.975-980
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• 1994

소변 속에 함유되어 있는 글루코우즈의 농도를 측정하기 위한 폴리우레탄 진단막의 제조과정과 조성조건들에 대해 조사하였다. 요당과 반응한 후 진단막에 나타난 색의 민감도와 안정성도를 증가시키기 위해서는 막 제조과정의 교반조건 및 교반용기, 그리고 사용되어지는 용매의 혼합비율이 아주 중요한 요소들로 작용됨을 알 수 있었다. 실질적으로 이러한 폴리우레탄을 이용해 얻어진 소변용 진단스트립을 사용하면 글루코우즈 농도가 30mg/dL에서 500mg/dL까지에서 색의 분리가 잘 이루어지므로, 이러한 농도 사이에서 요당의 정량적인 측정이 가능하여졌다.

• 대한화학회지
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• 제32권5호
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• pp.409-415
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• 1988

In this study, an aniline modified Bakelite-A resine was synthesized by polymerizing phenol, formaldehyde and aniline. Structural properties of the polymer were examined by IR spectroscopy, elemental analysis and vapour pressure osmometry. By visible spectroscopy, it was found that nitrogens of amine groups in the polymer are strongly coordinated to Ni(Ⅱ). Also a nitrate ion-selective PVC membrane electrode based on the polymer-Ni(Ⅱ) complex as ion carrier was preparaed. The electrode gave a linear response with a Nernstian slope within the concentration range $10^{-1}$ M∼$10^{-4}$M $KNO_3$.

• 공업화학
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• 제30권6호
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• pp.643-651
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• 2019

Polybenzimidazole (PBI), an engineering polymer with well-known excellent thermal, chemical and mechanical stabilities has been recognized as an alternative to high temperature polymer electrolyte membranes (HT-PEMs). This review focuses on recent advances made on the development of PBI-based HT-PEMs for fuel cell applications. PBI-based membranes discussed were prepared by various strategies such as structural modification, cross-linking, blending and organic-inorganic composites. In addition, intriguing properties of the PBI-based membranes as well as their fuel cell performances were highligted.

• 한국자기공명학회논문지
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• 제2권1호
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• pp.41-49
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• 1998

A linear undecapeptide, Substance P (SP) is involved in a wide variety of physiological processes such as pain, inflammation, salivation, and hypertension. Tertiary structure of SP in dodecylphosphocholine (DPC) micelles has been investigated by CD, NMR spectroscopy, and DGII calculation. CD spectrum of SP in the presence of 7.5 mM DPC micelles does not show any favorable secondary structure. The tertiary structure determined by NMR spectroscopy and DGII calculation shows that the Phe7-Phr8-Gly9-Leu10 region adopts a turn structure, while the N-terminal region is quite flexible. Both prolines in SP exist preferentially as the trans isoforms and the aromatic ring of Phe7 protrudes outward. Conformation of SP may be restrained by the contact of the Phe7 aromatic ring with the hydrophobic side chains of the DPC micelles and this interaction induces a turn structure. Structure of SP in aqueous solution in the presence of DPC micelles can represent a good model to study the conformation recognized by the receptor near neutral membrane.

• Journal of Microbiology
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• 제43권3호
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• pp.272-276
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• 2005

Bacillus subtilis ATCC 6633 was grown in BHIB medium supplemented with $Mn^{2+}$ for 96 h at $37^{\circ}C$ in a shaker incubator. After removing the microbial biomass, a lipopeptide biosurfactant was extracted from the supernatant. Its structure was established by chemical and spectroscopy methods. The structure was confirmed by physical properties, such as Hydrophile-Lipophile Balance (HLB), surface activity and erythrocyte hemolytic capacity. The critical micelle concentration (cmc) and erythrocyte hemolytic capacity of the biosurfactant were compared to those of surfactants such as SDS, BC (benzalkonium chloride), TTAB (tetradecyltrimethylammonium bromide) and HTAB (hexadecyltrimethylammonium bromide). The maximum hemolytic effect for all surfactants mentioned was observed at concentrations above cmc. The maximum hemolytic effect of synthetic surfactants was more than that of the biosurfactant produced by B. subtilis ATCC 6633. Therefore, biosurfactant would be considered a suitable surface-active agent due to low toxicity to the membrane.

• Journal of Pharmaceutical Investigation
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• 제22권1호
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• pp.23-31
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• 1992

A novel O-diethylaminoethyl chitosan (DEAE-chitosan) was synthesized via Schiff's reaction between chitosan and benzaldehyde. $C_2$ amino group was protected via Schiffs base reaction with benzaldehyde to form N-benzylidene chitosan. After reaction with diethylaminoethyl chloride, Schiffs base was removed by reacting O-diethylaminothyl-N-benzylidene chitosan and hydrochloric acid. Tensile strength of DEAE-chitosan was improved due to the incorporation of bulky side group in $C_6$ position of chitosan. DEAE-chitosan showed a pH-dependent swelling characteristics. Release rate of riboflavin was dependent on the water content of DEAE-chitosan that is a function of crosslinking degrees.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.41-47
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• 2004

This study was performed to investigate the antimicrobial effects of hetero-chitosans and their oligosaccharides on the halophilic bacterium, Vibrio parahaemolyticus. Nine classes of hetero-chitosan oligosaccharides were prepared based on their molecular weights, using an ultrafiltration membrane reactor system with chitosanase and celluase, from partially different deacetylated chitosans, 90%, 75%, and 50% deacetylated chitosan, respectively. Thirty-two strains of V. parahaemolyticus were isolated from various marine organisms such as shellfish, shrimps, octopus, and seabirds. Seventy-five percent deacetylated chitosan showed the highest antimicrobial acitivity. The minimal inhibitory concentration (MIC) was 0.5 mg/ml on 14 strains of V. parahaemolyticus, and MIC of the rest strains (18 strains) was 1.0 mg/ml. In addition, MIC of most hetero-chitosan oligosaccharides was 8.0 mg/ml. The results revealed that the antimicrobial effects of hetero-chitosans and their oligosaccharides against V. parahaemolyticus depend on the degree of deacetylation, their molecular weights, and strains tested.