• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1059-1065
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• 2012

Biocatalytic transfer of oxygen in isolated cytochrome P450 or whole microbial cells is an elegant and efficient way to achieve selective hydroxylation. Cytochrome P450 CYP105P2 was isolated from Streptomyces peucetius that showed a high degree of amino acid identity with hydroxylases. Previously performed homology modeling, and subsequent docking of the model with flavone, displayed a reasonable docked structure. Therefore, in this study, in a pursuit to hydroxylate the flavone ring, CYP105P2 was co-expressed in a two-vector system with putidaredoxin reductase (camA) and putidaredoxin (camB) from Pseudomonas putida for efficient electron transport. HPLC analysis of the isolated product, together with LC-MS analysis, showed a monohydroxylated flavone, which was further established by subsequent ESI/MS-MS. A successful 10.35% yield was achieved with the whole-cell bioconversion reaction in Escherichia coli. We verified that CYP105P2 is a potential bacterial hydroxylase.

• KSBB Journal
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• 제20권1호
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• pp.50-54
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• 2005

셀룰로오스의 탄화과정에서는 셀룰로오스의 pyrolysis에 의 해 생산된 타르에 의해 탄화 후, 셀룰로오스 탄화물의 섬유구조를 저해시키는 문제점이 존재한다. 이와 같은 결과는 $800^{\circ}C$이상의 탄화온도와 건조 셀룰로오스를 toluene에 침지하고 초음파 처리 후 탄화한 탄화물에서 감소되지만, 섬유구조만의 탄화물을 얻을 수 없었다. 그러나 셀룰로오스의 탄화에서 타르의 생산을 감소시키는 HCI vapor flow 조건에서의 열처리 과정의 적용과 탄화과정 중 생성된 타르의 제거를 통해서 탄화 후, 대부분의 영역에서 섬유 구조를 갖는 탄화물을 얻을 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제18권5호
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• pp.866-873
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• 2008

2-Deoxystreptamine is a core aglycon that is vital to backbone formation in various aminoglycosides. This core structure can be modified to develop hybrid types of aminoglycoside antibiotics. We obtained three genes responsible for 2-deoxystreptamine production, neo7, neo6, and neo5, which encode 2-deoxy-scyllo-inosose synthase, L-glutamine: 2-deoxy-scyllo-inosose aminotransferase, and dehydrogenase, respectively, from the neomycin gene cluster. These genes were cloned into pIBR25, a Streptomyces expression vector, resulting in pNDOS. The recombinant pNDOS was transformed into a non-aminoglycoside-producing host, Streptomyces venezuelae YJ003, for heterologous expression. Based on comparisons of the retention time on LC-ESI/MS and ESI-MS data with those of the 2-deoxystreptamine standard, a compound produced by S. venezuelae YJ003/pNDOS was found to be 2-deoxystreptamine.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1885-1889
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• 2012

Among 23 cytochrome P450s, CYP125A4 was proposed as a putative monooxygenase based on the high level of amino acid sequence homology (54% identity and 75% similarity) with the well characterized C27-steroid $Mycobacterium$ $tuberculosis$ CYP125A1. Utilizing MTBCYP125A1 as a template, homology modeling of SPCYP125A4 was conducted by Accelrys Discovery Studio 3.1 software. The modeled SPCYP125A4 structure with lowest energy value was subsequently assessed for its stereochemical quality and side-chain environment. The final model was generated by showing its active site through the molecular dynamics. The docking of steroids showed broad specificity of SPCYP125A4 with different orientation of ligand within active site facing the heme. One poses of C27-steroid with C26 facing the heme with distance of 3.734 ${\AA}$ from the Fe were predominant.

• Journal of Microbiology and Biotechnology
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• 제22권7호
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• pp.917-922
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• 2012

Homology modeling of Streptomyces peucetius CYP147F1 was constructed using three cytochrome P450 structures, CYP107L1, CYPVdh, and CYPeryF, as templates. The lowest energy SPCYP147F1 model was then assessed for stereochemical quality and side-chain environment by Accelrys Discovery Studio 3.1 software. Further activesite optimization of the SPCYP147F1 was performed by molecular dynamics to generate the final SPCYP147F1 model. The substrate limonene was then docked into the model. The model-limonene complex was used to validate the active-site architecture, and functionally important residues within the substrate recognition site were identified by subsequent characterization of the secondary structure. The docking of limonene suggested that SPCYP147F1 would have broad specificity with the ligand based on the two different orientations of limonene within the active site facing to the heme. Limonene with C7 facing the heme with distance of $3.4{\AA}$ from the Fe was predominant.

• 공업화학
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• 제16권2호
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• pp.257-261
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• 2005

미생물에 의해 생산된 셀룰로오스는 고등식물을 이루고 있는 셀룰로오스보다 순수한 형태로 존재하고 굵기가 20~50 nm인 fibril이 높은 배향성과 결정성으로 3차원적 망상구조를 이루고 있다. 이러한 미생물 셀룰로오스를 이용한 탄화과정의 적용은 기존의 PAN, Pitch, 재생 셀룰로오스(Rayon)를 사용한 탄소 섬유의 제조에서 얻지 못하는 섬유 구조 탄소 물질의 대량 생산을 가능하게 하고 탄화과정에 의해 생산된 섬유 구조의 탄화 셀룰로오스는 높은 결정성과 배향성을 갖는 나노 영역의 흑연 결정상의 섬유 제조를 가능하게 할 것이다. 탄화에 사용되는 셀룰로오스의 생산성에 대하여 세 가지 균주들에서 생산된 셀룰로오스의 양을 비교하여 G. xylinus ATCC 11142가 15mL 배지당 건조 질량 0.066 g의 셀룰로오스를 생산하는 것을 확인하였고 셀룰로오스의 탄화과정에서 셀룰로오스의 열분해에 의해 생산된 타르(tar)에 의해 탄화 후, 셀룰로오스 탄화물의 섬유 구조를 저해시키는 문제점이 존재한다. 이러한 문제를 해결하기 위하여 탄소 나노튜브의 정제과정에서 연구된 액상, 기상 그리고 초음파 처리를 통한 정제방법들을 적용하여, 탄화 셀룰로오스에서는 초음파 처리를 통한 정제과정의 적용이 셀룰로오스 탄화물에서 섬유 구조가 증가하는 결과를 나타냈다.

• Applied Microscopy
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• 제48권4호
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• pp.81-86
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• 2018

The respiratory chain complex forms a supercomplex (SC) in the inner mitochondrial membrane. This complex facilitates the process of electron transfer to produce the proton gradient used to synthesize ATP. Understanding the precise structure of the SC is considered an important challenge. However, it has not yet been reported. The development of a Cryo-electron microscopy (EM) technique provides an effective way to obtain high-resolution micrographs to determine the high-resolution three-dimensional structure of biomolecules. In this brief review, the currently reported Cryo-EM structures of the mammalian respirasome have been described in order to establish a direction for further research in the respiratory system.

• 대한수학회논문집
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• 제39권1호
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• pp.223-245
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• 2024

We study RNA foldings and investigate their topology using a combination of knot theory and embedded rigid vertex graphs. Knot theory has been helpful in modeling biomolecules, but classical knots emphasize a biomolecule's entanglement while ignoring their intrachain interactions. We remedy this by using stuck knots and links, which provide a way to emphasize both their entanglement and intrachain interactions. We first give a generating set of the oriented stuck Reidemeister moves for oriented stuck links. We then introduce an algebraic structure to axiomatize the oriented stuck Reidemeister moves. Using this algebraic structure, we define a coloring counting invariant of stuck links and provide explicit computations of the invariant. Lastly, we compute the counting invariant for arc diagrams of RNA foldings through the use of stuck link diagrams.

• KSBB Journal
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• 제23권1호
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• pp.44-47
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• 2008

Streptomyces peucetius가 생산하는 anthracycline 계열의 doxorubicin은 치료목적으로 사용되는 중요한 항암제 중 하나이다. Doxorubicin은 rhodomycin D에서부터 몇 단계의 생합성 과정을 더 거쳐 생산되는데, 생물학적 활성을 갖기 위해서는 deoxy-sugar의 전이가 반드시 일어나야 한다. 본 논문에서는 이종균주인 Streptomyces venezuelae에 11개의 유전자를 형질 전환하여 TDP-L-daunosamine를 생산하고 이것을 ${\varepsilon}$-rhodomycinone에 전이하여 rhodomycin D를 생산하는 연구를 수행하였다. S. peucetius 유래의 7개 유전자 dnmU, T, J, V, Z, Q, S.를 당 합성 및 전이를 위해 plasmid 형태로 전이하였으며, S. venezuelae의 desIII, IV와 doxorubicin 내성 유전자인 drrA, B는 chromosomal DNA에 삽입하였다. Aglycone 기질인 ${\varepsilon}$-rhodomycinone을 확보하기 위하여 6L의 고체 배지에 S. peucetius를 배양하여 유기용매로 추출하고 preparative HPLC로 분리 정제하였다. 결과적으로 이종균주인 S. venezuelae에서 ${\varepsilon}$-rhodomycinone에 당 전이가 일어난 생산물을 확인함으로써 deoxy-sugar의 생합성 및 전이에 필요한 최소한의 유전적 정보를 확인할 수 있었다. 또한, 유사서열 단백질 모델링을 통하여, 최초로 당 전이 반응에 필수적인 도움효소 DnrQ의 구조를 예측하였다.

• Journal of Photoscience
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• 제3권1호
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• pp.23-28
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• 1996

To investigate the structure and function of photosystem I, cartridge mutagenesis technique was used to inactivate the psaB gene of photosystem I. From the screen, many strains which have potential defects in photosystem I were generated. Biochemical analysis revealed that B2, one of the mutant, had a reduced amount of chlorophyll. Electron transfer activitx from photosystem II to photosystem I as oxygen uptake was the rate of 64 % of wild type. Also B2 showed a decreased photosystem I activity when measured by 77 K fluorescence emission spectrum. Particularly, immunodetection analysis showed that the B2 had reduced amount of PsaA/PsaB, but a normal range of PsaC and PsaD. Here we present a photoheterotrophic mutant for psaB gene as a unique model strain for future study of structural/functional relationship and biogenesis of photosystem I.