• Bulletin of the Korean Chemical Society
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• 제22권5호
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• pp.523-526
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• 2001

• Journal of Microbiology and Biotechnology
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• 제9권4호
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• pp.404-413
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• 1999

Methanopyrus kandleri is a hyperthermophilic methanogen that represents one of the most heat-resistant organisms: the maximum growth temperature of M. kandleri is $110^{\circ}C$. A random sequence analysis of the genomic DNA of M. kandleri has been performed to obtain genomic information. More than 200 unique sequence tags were obtained and compared with the sequences in the GenBank and PIR databases. About 30% of the analyzed tags showed strong sequence similarity to previously identified genes involved in various cellular processes such as biosynthesis, transport, methanogenesis, or metabolism. When statistics relating to the frequency of codons were examined, the sequenced open reading frames showed highly biased codon usage and a high content of charged amino acids. Among the identified genes, a homologue of the catalytic subunit of carbon monoxide dehydrogenase (CODH) that reduces $CO_2$ to CO was cloned and sequenced in order to examine its detailed gene structure. The cloned gene includes consensus promoters. The amino acid sequence of the cloned gene shows a strong homology with the CODH genes from methanogenic Archaea, especially in the presumed binding sites for Fe-S centers.

• Bulletin of the Korean Chemical Society
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• 제26권1호
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• pp.151-156
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• 2005

The conformational dynamics of heme pocket, a small vacant site near the binding site of heme proteins -myoglobin (Mb) and hemoglobin (Hb), was investigated after photolysis of carbon monoxide from MbCO and HbCO in D$_2$O solution at 283 K by probing time-resolved vibrational spectra of photolyzed CO. Two absorption bands, arising from CO in the heme pocket, evolve nonexponentially in time. The band at higher energy side blue shifts and broadens with time and the one at lower energy side narrows significantly with a negligible shift. These spectral evolutions are induced by protein conformational changes following photolysis that modify structure and electric field of heme pocket, and ligand dynamics in it. The conformational changes affecting the spectrum of photolyzed CO in heme pocket likely modulates ligand-binding activity.

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1314-1320
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• 2004

The adsorption and configuration of CO molecules adsorbed on W (110) and W (100) surfaces have been calculated by the atomic superposition and electron delocalization molecular orbital (ASED-MO) method. Referred to as the ASED-MO method, it has been used in the present study to calculate the geometries, binding energies, vibrational frequencies, orbital energies, reduced overlap population (ROP), and charges. From these results adsorption properties of ${\alpha}$-state and ${\beta}$-state were deduced. The calculated binding energies are in good agreement with the experimental result. On the W (110), the calculated average binding energies are 2.56 eV for the end-on configuration and 3.20 eV for the lying-down configuration. Calculated vibrational frequency is 1927 $cm^{-1}$ at a 1-fold site and 1161 $cm^{-1}$ at a long-bridge (2) site. These results are in reasonable agreement with experimental values. On the W(100) surface, calculated average binding energies of the end-on and the lying-down are 2.54 eV and 4.02 eV respectively. The differences for binding energy and configuration on the surfaces are explained on the basis of surface-atom coordination and atom-atom spacing. In the favored lyingdown CO configuration on the W(110) and W(100) surfaces, 4 ${\sigma}$ and 1 ${\pi}$ donation interactions, coupled with the familiar 5 ${\sigma}$ donation to the surfaces and back-donations to the CO 2 ${\pi}^{\ast}$ orbital, are responsible for adsorption to the surface.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2019년도 정기학술대회 발표논문집
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• pp.83-83
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• 2019

Increasing the CO₂ concentration in the atmosphere induce high temperature and rising sea levels. So the technology that capture and reuse of the CO₂ have been recently become popular. Among other methods, CRR(CO2₂ reduction reaction) is typical method of CO₂ reusing. Electrocatalyst can show more higher efficiencies in CRR than photocatalyst because it doesn't use nature source. Nowadays, finding high efficient electrocatalyst by controlling electronic (affected by stoichiometry) and geometric (affected by atomic arrangement) factors are very important issues. Mono-atomic electro-catalyst has limitations on controlling binding energy because each intermediate has own binding energy range. So the Multi-metallic electro-catalyst is important to stabilize intermediate at the same time. Carbon monoxide(CO) which is our target product and important feedstock of useful products. Au is known for the most high CO production metal. With copper, Not only gold/copper has advantages which is they have FCC packing for easily forming solid solution regardless of stoichiometry but also presence of adsorbed CO on Cu promotes the desorption of CO on Au because of strong repulsion. And gold/copper bi-metal catalyst can show high catalytic activity(mass activity) although it has low selectivity relatively Gold. Actually, multi-metallic catalyst structure control method is limited in the solution method which is takes a lot of time. In here, we introduce CTS(carbo thermal shock) method which is using heat to make MMNP in a few seconds for making gold-copper system. This method is very simple and efficient in terms of time(very short reaction time and using carbon substrate as a direct working electrode) and increasing reaction sites(highly dispersed and mixing alloy structures). Last one is easy to control degree of mixing and it can induce 5 or more metals in one alloy system. Gold/copper by CTS can show higher catalytic activity depending on metal ratio which is altered easily by changing simple variables. The ultimate goals are making CO₂ test system by CTS which can check the selectivity depending on metal types in a very short time.

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.532-541
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• 2010

Peroxidase-like activity of Vitreoscilla hemoglobin (VHb) has been recently disclosed. To maximize such activity, two catalytically conserved residues (histidine and arginine) found in the distal pocket of peroxidases have successfully been introduced into that of the VHb. A 15-fold increase in catalytic constant ($k_{cat}$) was obtained in P54R variant,which was presumably attributable to the lower rigidity and higher hydrophilicity of the distal cavity arising from substitution of proline to arginine. None of the modifications altered the affinity towards either $H_2O_2$ or ABTS substrate. Spectroscopic studies revealed that VHb variants harboring the T29H mutation apparently demonstrated a spectral shift in both ferric and ferrous forms (406-408 to 411 nm, and 432 to 424-425 nm, respectively). All VHb proteins in the ferrous state had a $\lambda_{soret}$ peak at ~419 nm following the carbon monoxide (CO) binding. Expression of the P54R mutant mediated the downregulation of iron superoxide dismutase (FeSOD) as identified by two-dimensional gel electrophoresis (2-DE) and peptide mass fingerprinting (PMF). According to the high peroxidase activity of P54R, it could effectively eliminate autoxidation-derived $H_2O_2$, which is a cause of heme degradation and iron release. This decreased the iron availability and consequently reduced the formation of the $Fe^{2+}$-ferric uptake regulator protein ($Fe^{2+}$-Fur), an inducer of FeSOD expression.

• 대한화학회지
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• 제33권5호
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• pp.558-567
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• 1989

여러가지 조성비로 만든 Cu/ZnO계 촉매로 이산화탄소를 수소화시켜 메탄올을 합성하였다. 촉매제조시 각 성분의 조성비가 촉매활성에 미치는 영향을 조사하고 반응촉매에 대하여 표면적 측정(BET), 주사전자현미경 측정(SEM), X선회절분석(XRD), X선광전자분석(XPS) 등을 실시하여, 각 촉매의 촉매특성을 조사하고 촉매활성과의 연관성을 연구하였다. 반응생성물은 메탄올과 일산화탄소 뿐이었는데 메탄올의 생성은 CuO의 함량이 증가하면 그에 따라 점차 증가하였으나 CuO:ZnO의 조성비율이 30:70일 경우에 최대이었고, CuO가 70 이상이면 급격하게 감소하였다. 촉매에 대한 SEM 측정과 BET 측정결과에서 확인된 바와 같이 이점은 미세결정크기가 증가되고 표면적이 감소하는 점과 일치되었다. 또 XPS 측정결과에서 촉매표면상에서의 Cu의 농도는 Cu/Cu+Zn(atomic ratio)을 비교할 때 CuO의 함량이 50% 이상인 경우에서 현저히 감소하였다. 그리고 각 촉매들의 $Cu(2P^3)$에 대한 결합에너지의 수치상의 값은 거의 같았으나 환원된 상태의 $Cu(2P^3)$의 결합에너지는 소성된 상태의 것과 비교하여 낮아졌고, 표면에 분포된 Cu 는 대부분 $Cu^{\circ}$로 확인되었으며 CuO:ZnO의 조성이 30:70인 경우에서 최대가 되었다. 이것은 또한 CuO의 조성비율이 30인 때에 메탄올생성이 최대라는 실험결과와도 잘 일치하였다. 그리고 환원된 각각의 촉매로 펄스(pulse)형태의 반응기에서 이소프로판올을 분해시킨 결과 아세톤의 생성율이 프로필렌보다 컸음으로 이들은 염기성이 상대적으로 강한 촉매라고 추측하였다.