• Archives of Pharmacal Research
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• 제27권5호
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• pp.502-506
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• 2004

Two series of 2-(5-nitro-2-furyl)- and 2-(1-methyl-5-nitro-1H-imidazol-2-yl)-5-propyl, allyl and propargyl)thio-1,3,4-thiadiazoles (6a-f) and 2-(5-nitro-2-furyl)- and 2-(1-methyl-5-nitro-1 H-imidazol-2-yl)-5-(nitrobenzyl)thio-1,3,4-thiadiazole derivatives (8a-f) have been synthesized and evaluated against Mycobacterium tuberculosis, as part of the TAACF TB screening program under direction of the US National Institute of Health, the NIAID division. Primary screening was conducted at a single concentration, 6.25 $\mu\textrm{g}$mL$^{-1}$ , against M. tuberculosis H$_{37}$ Rv in BACTEC 12B medium, using the Microplate Alamar Blue Assay (MABA). The minimum inhibitory concentration (MIC) was determined for the compounds that demonstrated $\geq$90% growth inhibition in the primary screening. A varying degree of antituberculosis activity (from 0-97% of growth inhibition) was observed with the alkylthio series (6a-f), and the nitroimidazole derivative with a propylthio group (6b) and the nitrofuran derivative with a propargylthio group (6e), were the most active compounds (MIC=3.13 and 1.56 /$\mu\textrm{g}$mL$^{-1}$ , respectively). Among the nitrobenzylthio derivatives (8a-f), all the ortho, meta and para nitrobenzyl isomers in the nitrofuran series exhibited good antituberculosis activity (MIC=3.13 $\mu\textrm{g}$mL$^{-1}$ ), while the corresponding nitroimidazole analogues were completely inactive (Inhibition=0%).

• KSBB Journal
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• 제5권2호
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• pp.141-149
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• 1990

$\beta$-glucosidase derived from Aspergillus niger was immobilized by (1) covalent linkage on chitin and chitosan with glutaraldehyde, (2) adsorption on DEAE-cellulose and Amberite IRA93 after succinylation, and (3) entrapment on alginate and polyacrylamide gels with various cross linking agents. The retention yield of $\beta$-glucosidase immobilized on chitosan was 31.5% and operational stability was 69% after continuous operation at column reactor(5$0^{\circ}C$ at pH 4.8) for 15 days. The retention yield and operational stability were 24.7% and 60% respectively, in adsorption on Amberite IRA 93. On the other hand, the entrapment method by alginate and polyacrylamide gel was identified to be not appropriate due to the continuous elution of inlmobilized $\beta$-glucosidase. Optimum conditions for the immobilization on chitosan were also studied with optimum pH of 4.8 and glutaraldehyde concentration of 0.4%(w/v). The properties and stability of immobilized $\beta$-glucosidase are also investigted. The conversion yield of cellobiose to glucose was also analyzed using the column type enzyme reactor to evaluate the effectiveness of immobilized enzyme.

• Food Engineering Progress
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• 제15권3호
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• pp.276-281
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• 2011

The optimum condition for the extraction and purification processes of phytic acid from defatted rice bran was examined. The phytic acid was efficiently extracted when the defatted rice bran was treated with 10 volumes of 0.5% HCl for 1 hr. For the neutralization of acid-treated extract, 0.5% NaOH was the most acceptable. To purify phytic acid, Diaion HP20 resin was used to remove impurities from the extract. The flow-through was then loaded onto ion exchange columns packed with various resins and among them, Amberlite IRA-416 resin showed highest recovery yield. When the phytic acid was absorbed onto Amberlite IRA-416 resin and then eluted with 0.5% NaOH, 89% of applied phytic acid was eluted. Most proteins were removed from the purified phytic acid and total protein content of the phytic acid was 0.14%(w/w).

• Journal of Microbiology and Biotechnology
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• 제1권1호
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• pp.63-69
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• 1991

Performance of column type bioreactor packed with immobilized cyclodextrin glucanotransferase (CGTase) on chitosan and Amberite IRA 900 was evaluated for cyclodextrin(CD) production. For CGTase immobilized on chitosan, the maximum CD conversion yield of 42% was achieved at the range of 88-168 units of immobilizied CGTase per gram of chitosan, retention time of 0.3 hr, and from 5.0% (w/v) of partially cyclized soluble starch. On the other hand, for CGTase immobilized on Amberite IRA 900, the maximum conversion yield of 40% was obtained at the range of 3.6-11.0 units of immobilized CGTase per gram of carrier and retention time of 1.2 hr from 5.0% of substrate. Above CD conversion yields are almost identical level with that can be obtained with soluble CGTase of 47%. The productivities of bioreactor packed with immobilized CGTase were 17.0g of CD/lㆍhr for amberite IRA 900 and 15.5g of CD/lㆍhr for chitosan. The partially cyclized starch with soluble CGTase were more suitable as substrate to achieve better CD conversion yield, and 5% (w/v) of partially cyclized soluble starch containing 10% (w/w) of CD was found to be most suitable to obtain maximum CD conversion yield.

• The Microorganisms and Industry
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• 제19권4호
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• pp.32-35
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• 1993

ras는 활성화 형태인 GTP bound form과 비활성화 형태인 GDP bound form의 두 형태로 존재하며 두 형태를 매개하는 regulatory protein들에 의해 그 activity가 조절된다. 또한 ras는 GTP와 GDP에 강한 친화성이 있으며 세포내에는 GTP보다 GDP가 더 많이 있어서 평소에는 ras가 GDP와 결합하고 있다가 활성화될때만 GTP와 결합하는 것으로 추정된다. GDP bound ras는 guanine nucloetide exchange protein(GEP)에 의해 활성화된 GTP bound form으로 전환되며 ras의 기능이 발휘된 후에는 GTPase activating protein(GAP)에 의해 비활성화된다. Yeast의 경우 IRA1과 2의 product가 GAP의 역할을 하는 것으로 알려져 있고 CDC25 gene의 product가 GEP의 기능을 담당하는 것으로 알려져 있다. NF1 gene은 Von Recklinghausen Neurofibromatosis Type I 질병을 가진 환자에게서 발견되었는데 부분적으로 sequencing한 결과에 따르면 yeast의 IRA1/2, mammalian GAP gene product와 protein homology가 높은 것으로 나타났다. Yeast의 경우 IRA1/2 gene의 손실이나 mammalian ras gene의 transformation으로 인한 heat shock sensitivity가 NF1 gene(2,3) 혹은 GAP(4)의 expression으로 suppression된 것으로 보아 NF1이 GAP protein으로서 ras를 불활성화 시킨다는 것이 판명되었다. 결론적으로 ras의 활성은 GTP bound 혹은 GDP bound의 양쪽형태를 이동하면서 조절되는데 이 기능은 GAP과 GEP 또는 그의 유사 protein들에 의해 수행되며 이러한 regulatory protein들은 growth factor, cytokine 그리고 protein kinase 같은 signal에 의해 활성화된다고 생각된다. 본 총설에서는 ras protein의 여러가지 성질보다는 ras의 modification과 관련하여 항암제로 사용할 수 있는 ras에 specific한 약품개발의 가능성과 현재 알려진 ras의 inhibitor를 중심으로 논하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 한국정보처리학회 2006년도 춘계학술발표대회
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• pp.489-492
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• 2006

IDA(Inter-Domain Authentication)는 한 영역의 클라이언트가 다른 영역의 서버에 접근이 가능하게 하는 인증 메카니즘이다. 기존의 커버러스 인증 메카니즘에는 IRA(Inter-Realm Authentication)를 제공하고 있지만 모든 인증방식이 커버러스로 구현된 경우에만 가능하다. 현재 재버의 표준으로는 커버러스 이외에 다른 인증 메카니즘이 병존할 수 있기 때문에 커버러스의 IRA로는 지원이 불가능하다. 따라서 본 연구에서는 재버의 환경에서 다양한 인증 메카니즘이 존재하는 경우에도 적용할 수 있는 IDA를 제안한다. 이 메카니즘을 사용함으로써 중복저장과 동기화에 대한 문제를 해결하여 분산 응용프로그램을 용이하게 설계 구축 할 수 있다.

• KSBB Journal
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• 제8권5호
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• pp.417-423
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• 1993

The effect of moisture content of biocatalyst on the performance of a gas phase continuous bioreactor was investigated along with study on the mass transfer limitation. The biocatalysts whose moisture contents are 46.2% and 37.2%, respectively were prepared by immobilization of alcohol oxidase on Amberlite IRA-400, following by slow dehydration method, and packed into a column. Relative production rate (RPR), acetaldehyde composition ($X_p$) and conversion (X) of biocatalysts (37.2%) are better than those of biocatalysls (46.2%), and it was considered that these are attributed to the mass transfer enhancement in the gas phase compared with the aqueous phase.

• Polymer(Korea)
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• 제30권1호
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• pp.45-49
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• 2006

In this study, it was investigated on the boron separation ken synthetically prepared seawater. ion exchange resin used in the experiments was Amberlite IRA 743, containing glucamine functional group. The experiments were carried out as a function of the conditions of the pH, boron initial concentration and temperature of seawater in a batch reactor. As a result, optimum conditions for boron adsorption were at pH 8.5 and 313 K, respectively. The adsorption rate was increased very fast with increasing the temperature, but decreased with increasing the initial concentration of boron. Also, the kinetics for boron adsorption applied the pseudo-second order model, as follows: $$\frac{X}{1-X}=780[C_0]^{-1.65}t^{1.48}\;exp\;({-\frac{17883}{RT}}\)\;;\;pH8.5$$

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권3호
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• pp.174-180
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• 2000

Cyclodextrin glucanotransferase (CGTasa) from Thermoanaerobacter sp. was adsorbed on the ion exchange resin Amberlite IRA-900. The optimum conditions for the immobilization of the CGTase were pH6.0 and 600 U CGTase/g resin, and the maximum yield of immobilization was around 63% on the basis of amount ratio of the adsorbed enzyme to intial amount in the solution. Immobilixation of CGTase shifted the optimum temperature for the enzyme to peoduce transglycosylated xylitol from 7$0^{\circ}C$ to 9$0^{\circ}C$ and improved the thermal stability of immobilized CGTase, especially after the addition of soluble starch and calcium ions. Transglycosylated xylitol was continuoncly produced using immobilized CGTase in the column type packed bed reactor, and the operating conditions for maximum yield were 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) xylitor as the glycosyl acceptor, 20mL/h of medium fiow rate, and 6$0^{\circ}C$. The maximum yield of transglycosylated xylitol and productivity were 25% and 7.82 g.L-1.h-1, respectively. The half-life of the immobilized CGTase in a column type packed bed reactor was longer than 30 days.

• KSBB Journal
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• 제11권5호
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• pp.529-535
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• 1996

Methyl frucloside was purified from the aqueous sugar/methyl fructoside solution by liquid chromatography using Amberlite IRA-900, strong anion-exchange resin. The optimum operating conditions, resolution and productivity of methyl fructoside were discussed to evaluate the practical feasibility of the proposed chromatographic separation process of methyl fructoside which is useful as a new starting material for sugar ester synthesis. The linear chromatography model with HETP was well applied to the chromatographic separation process of methyl fructoside and the theoretical solution successfully predicted the elution chromatogram of methyl fructoside and sucrose at different superficial linear velocity of eluent for rectangular feed with different loading volume of packed bed. The optimum operating conditions were found to be 75% with the loading volume of packed bed at 1.13 cm/min of the superficial linear velocity at $60^{\circ}C$, and gave the productivity of methyl fructoside of 7 mg/g-resin/h with the resolution of 1.1.