• Applied Microscopy
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• 제30권4호
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• pp.413-421
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• 2000

초고온 archaeon인 Thermococcus profundus에서 실린드형태의 단백질 복합체를 분리, 생화학적 특성과 구조를 규명하였다. 전자현미경과 영상처리 (image processing)를 이용한 구조 분석으로 8개의 subunit으로 이루어진 링 (ring) 형태가 두 개 겹쳐져 가운데 통로를 가지는 실린드형태로 이루어진 복합체임을 알 수 있었다. 또한 60kDa단백질(P60 complex)로 구성된 homomultimer임을 보여 주고 있다. 이 복합체는 $80^{\circ}C$ 이상에서 도 강한 ATPase의 활성을 보여주는 강한 내열성 단백질임을 알 수 있다. P60 complex는 초고온 archaeon이 높은 온도에서 적응하며 생존하는데 매우 중요한 역할을 할 것으로 추정할 수 있다.

• Applied Microscopy
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• 제30권2호
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• pp.185-191
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• 2000

초고온 archaeon인 Thermococcus profundus에서 매우 거대한 단백질 복합체를 분리 및 구조를 규명하였다. 거대 복합체는 93kDa단백질(P93 complex)로 구성된 homomultimer이며, 강한 내열성을 보여주고 있다. 순수 분리한 P93 complex를 SDS(최종 농도 1%)와 $85^{\circ}C$에서 12시간 항온시킨 후, SDS-PAGE와 전자현미경에서 구조적 변화를 관찰할 수 없었다. 음착색된 P93 complex의 전자현미경 사진에서 하나의 형태만을 보여주고 있으며, 구조의 규명을 위해 image processing을 하였다. 이의 구조는 3대칭 중심에 core(혹은 hole)이 뚜렷이 존재하며 이를 중심으로 단백질이 모여 있는 형태를 보여 주고 있다. 또한 P93 complex는 가장자리에서 뚜렷한 형태를 보여주지 않은 부분, 즉 flexible부분을 포함하고 있다. Gel filtration과 2차원 구조를 기초로 P93 complex는 24 homomultimer로 되어 있음을 추정하였다.

• KSBB Journal
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• 제26권3호
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• pp.237-242
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• 2011

As a number of archaea are ubiquitously found in non-extreme habitats, elucidation of their functional roles becomes currently an emerging issue. However, most of them are unable to grow in pure culture and so it remains to be established. In order to find genes lacking in the genome of an ammonia-oxidizing archaeon (AOA), we here report on the comparative analyses of an AOA genome with those of experimentally or theoretically established minimal genomes for independent growth. We assessed the genes lacking in AOA using logic of clusters of orthologous groups (COG), remote homology, consensus sequence weight matrix, function-based motif or domain, and then further excluded genes encoding hypothetical orarchaea-specific proteins. The results of these combination analyses revealed 19 candidate genes lacking in the genome of an AOA. Thus, our results provide a possibility of inducing independent growth of AOA when supplemented with product (s) of the lacking gene (s), and also give a chance for finding new proteins with novel sequence or structure space even if the predicted lacking-genes will be found using another algorithms or biochemical studies.

• 한국유전체학회:학술대회논문집
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• 한국유전체학회 2005년도 The 14th Korea Genome Conference
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• pp.36-36
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• 2005

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권2호
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• pp.115-118
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• 1998

Utilization of yeast extract and formation of byproduct metabolite were investigated for hyperthermophilic archaeon Sulfolobus solfataricus (DSH 1617). In both batch and fed-batch cultivations of S. solfataricus, maximal cell density, {{{{ { NH}`_{4 } ^{ +} }}} ion production and pH change were highly dependent on the ratio of yeast extract to glucose in the medium. Variation of {{{{ { NH}`_{4 } ^{ +} }}}} ion level was identified as a major cause of pH change during cultivation, and acidification of culture broth was attributed to consumption of {{{{ { NH}`_{4 } ^{ +} }}}} ions rather than formation of acid byproducts. It was also observed that increase of {{{{ { NH}`_{4 } ^{ +} }}}} ion concentrations in the medium resulted in greater degree of growth inhibition.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권1호
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• pp.53-56
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• 2000

A thermostable esterase from the hyper thermophilic archaeon Sulfolobus solfataricus was partially purified 590-fold with $16.2\%$ recovery. The partially purified esterase had a specific activity of $29.5\;{\mu}mol\;min^{-1}mg^{-1}$ when the enzyme activity was determined using p-nitrophenyl butyrate as a substrate. The apparent molecular weight was about 100 kDa, while the optimum temperature and pH for esterase were $75^{\circ}C$ and 8.0, respectively. The enzyme showed high thermal stability and solvent tolerance in comparison to its mesophilic counterpart. The enzyme also showed chiral resolution activity for (S)-ibuprofen, indicating that S. solfataricus esterase can be used for the production of commercially important chiral drugs.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권4호
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• pp.344-350
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• 2006

Thermoplasma acidophilum is a thermoacidophilic archaeon that grows optimally at $59^{\circ}C$ and pH 2. Along with another thermoacidophilic archaeon, Sulfolobus solfataricus, it is known to metabolize glucose by the non-phosphorylated Entner-Doudoroff (nED) pathway. In the course of these studies, the specific activities of glyceraldehyde dehydrogenase and glycerate kinase, two enzymes that are involved in the downstream part of the nED pathway, were found to be much higher in T. acidophilum than in S. solfataricus. To characterize glycerate kinase, the enzyme was purified to homogeneity from T. acidophilum cell extracts. The N-terminal sequence of the purified enzyme was in exact agreement with that of Ta0453m in the genome database, with the removal of the initiator methionine. Furthermore, the enzyme was a monomer with a molecular weight of 49kDa and followed Michaelis-Menten kinetics with $K_m$ values of 0.56 and 0.32mM for DL-glycerate and ATP, respectively. The enzyme also exhibited excellent thermal stability at $70^{\circ}C$. Of the seven sugars and four phosphate donors tested, only DL-glycerate and ATP were utilized by glycerate kinase as substrates. In addition, a coupled enzyme assay indicated that 2-phosphoglycerate was produced as a product. When divalent metal ions, such as $Mn^{2+},\;CO^{2+},\;Ni^{2+},\;Zn^{2+},\;Ca^{2+},\;and\;Sr^{2+}$, were substituted for $Mg^{2+}$ the enzyme activities were less than 10% of that obtained in the presence of $Mg^{2+}$. The amino acid sequence of T. acidophilum glycerate kinase showed no similarity with E. coli glycerate kinases, which belong to the first glycerate kinase family. This is the first report on the biochemical characterization of an enzyme which belongs to a member of the second glycerate kinase family.

• Ocean and Polar Research
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• 제39권4호
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• pp.269-277
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• 2017

Medium compositions for the hyperthermophilic archaeon, Thermococcus onnurineus NA1 was statistically optimized to enhance formate-driven hydrogen ($H_2$) production by using response surface methodology. From the Plackett-Burman design-based experiment, it was confirmed that among the minor components of medium such as KCl, $MgSO_4$, $NH_4Cl$, Cystein-HCl, trace elements, Fe-EDTA and $CaCl_2$, the trace elements were screened as the only positively effective components with respect to $H_2$ production. Subsequently, the optimal concentrations of the trace elements and the major components of a medium such as NaCl, yeast extract and sodium formate were determined from the five-level central composite design (CCD)-based experiment. The resulting quadratic model predicted the maximum $H_2$ production of 46.6 mmol/L in serum bottle and it was validated experimentally using the optimal medium initially supplemented with 26.70 g/L of NaCl, 9.81 g/L of sodium formate, 3.50 g/L of yeast extract and 4.59 mL/L of trace elements. From the duplicate batch cultivations in the fermentor using the optimized medium, the a maximum $H_2$ production rate up to 71.8 mmol/L/h could be obtained, which was a 65% enhanced value compared with that obtained using the control medium, showing the high efficiency of the optimized medium.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.479-479
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• 2003

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.536-536
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• 2005