• BMB Reports
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• 제39권4호
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• pp.426-431
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• 2006

Embryonic stem cells (ESCs), representing a population of undifferentiated pluripotent cells with both self-renewal and multilineage differentiation characteristics, are capable of spontaneous differentiation into cardiomyocytes. The present study sought to define the kinetic characterization of lactate dehydrogenase (LDH) and creatine kinase (CK) of ESC- and neonatal-derived cardiomyocytes. Spontaneously differentiated cardiomyocytes from embryoid bodies (EBs) derived from mouse ESC line (Royan B1) and neonatal cardiomyocytes were dispersed in a buffer solution. Enzymes were extracted by sonication and centrifugation for kinetic evaluation of LDH and CK with spectrophotometric methods. While a comparison between the kinetic properties of the LDH and CK of both groups revealed not only different Michaelis constants and optimum temperatures for LDH but also different Michaelis constants and optimum pH for CK, the pH profile of LDH and optimum temperature of CK were similar. In defining some kinetic properties of cardiac metabolic enzymes of ESC-derived cardiomyocytes, our results are expected to further facilitate the use of ESCs as an experimental model.

• 대한예방한의학회지
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• 제12권1호
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• pp.73-87
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• 2008

In recent years, there has been a globally increasing application of herbal medicines and dietary supplements to treat various chronic diseases and to promote health. However, there are increasing clinical reports on the organ toxicities associated with consumption of herbal medicines. In general, most xenobiotics are metabolized by Phase I reaction(the main enzyme : cytochrome P450) and Phase II reaction. However, reactive oxygen species, free radicals and electrophils are produced inevitably during xenobiotics metabolism. These toxic species and metabolites are increased whenever the endogenous substances and enzymes for Phase II reaction not available. In addition, herbal-drug interactions are pharmacokinetic, with most actually or theoretically affecting the metabolism of the affected product by way of the cytochrome P450 enzymes. This review updated the knowledge on metabolic activation of herbal components and its clinical and toxicological implications. Also, the possible way for preventing the side-effects by herbal-medicine use was suggested.

• Plant Biotechnology Reports
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• 제5권1호
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• pp.89-103
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• 2011

Two rice varieties, viz. Nonabokra and Pokkali, have been evaluated for their responses to salinity in terms of some physiological and biochemical attributes. During the exposure to salinity (200 mM concentration of sodium chloride for 24, 48, and 72 h), a significant increase in sodium was recorded which was also concomitant with the changes of other metabolic profiles like proline, phenol, polyamine, etc. The protein oxidation was significantly increased and also varied between the two cultivars. The changes in activities of anti-oxidative enzymes under stress were significantly different to the control. The detrimental effects of salinity were also evident in terms of lipid peroxidation, chlorophyll content, protein profiles, and generation of free radicals; and these were more pronounced in Pokkali than in Nonabokra. The assessment and analysis of these physiological characters under salinity could unravel the mechanism of salt responses revealed in this present study and thus might be useful for selection of tolerant plant types under the above conditions of salinity.

• Toxicological Research
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• 제30권1호
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• pp.33-38
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• 2014

The human cytochrome P450 2J2 catalyzes an epoxygenase reaction to oxidize various fatty acids including arachidonic acid. In this study, three recombinant enzyme constructs of P450 2J2 were heterologously expressed in Escherichia coli and their P450 proteins were successfully purified using a $Ni^{2+}$-NTA affinity column. Deletion of 34 amino acid residues in N-terminus of P450 2J2 enzyme (2J2-D) produced the soluble enzyme located in the cytosolic fraction. The enzymatic analysis of this truncated protein indicated the typical spectral characteristics and functional properties of P450 2J2 enzyme. P450 2J2-D enzymes from soluble fraction catalyzed the oxidation reaction of terfenadine to the hydroxylated product. However, P450 2J2-D enzymes from membrane fraction did not support the P450 oxidation reaction although it displayed the characteristic CO-binding spectrum of P450. Our finding of these features in the N-terminal modified P450 2J2 enzyme could help understand the biological functions and the metabolic roles of P450 2J2 enzyme and make the crystallographic analysis of the P450 2J2 structure feasible for future studies.

• BMB Reports
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• 제47권7호
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• pp.361-368
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• 2014

Lipid components in biological membranes are essential for maintaining cellular function. Phosphoinositides, the phosphorylated derivatives of phosphatidylinositol (PI), regulate many critical cell processes involving membrane signaling, trafficking, and reorganization. Multiple metabolic pathways including phosphoinositide kinases and phosphatases and phospholipases tightly control spatio-temporal concentration of membrane phosphoinositides. Metabolizing enzymes responsible for PI 4,5-bisphosphate (PI(4,5)P2) production or degradation play a regulatory role in Toll-like receptor (TLR) signaling and trafficking. These enzymes include PI 4-phosphate 5-kinase, phosphatase and tensin homolog, PI 3-kinase, and phospholipase C. PI(4,5)P2 mediates the interaction with target cytosolic proteins to induce their membrane translocation, regulate vesicular trafficking, and serve as a precursor for other signaling lipids. TLR activation is important for the innate immune response and is implicated in diverse pathophysiological disorders. TLR signaling is controlled by specific interactions with distinct signaling and sorting adaptors. Importantly, TLR signaling machinery is differentially formed depending on a specific membrane compartment during signaling cascades. Although detailed mechanisms remain to be fully clarified, phosphoinositide metabolism is promising for a better understanding of such spatio-temporal regulation of TLR signaling and trafficking.

• 한국균학회지
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• 제23권1호통권72호
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• pp.86-91
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• 1995

Rhizopus oryzae의 카드뮴 적응 및 해독기작과 이에 관련된 세포내 생리 생화학적 변화를 조사하였다. R. oryzae는 카드뮴을 첨가 배양하였을 때 카드뮴 영향하에서는 carbohydrate metabolic pathway에 관련된 효소 활성(MDH, GPI)이 촉진되고 과산화물 제거에 관여하는 효소가 새롭게 유도(CAT2)된 반면, lactate를 이용하는 효소(LDH, ADH)의 활성이 감소된 사실은 중금속 영향하에서 세포의 성장과 에너지 공급을 위해 에너지 수율이 낮은 lactate를 이용하는 경로보다는 에너지 수율이 높은 TCA cycle 경로에 작용하는 효소들과 독성과산화물 제거에 관여하는 효소의 더 많은 derepression이 필요하다는 것을 알 수 있었다.

• 미생물학회지
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• 제45권1호
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• pp.32-40
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• 2009

수변 낙엽퇴적층에서 호열성 세균의 분포와 물질분해 양상을 파악하기 위하여, 호열성 세균을 분리하고 그 특성을 조사하였다. 고분자 유기물의 분해력이 높고 $60^{\circ}C$에서 생장하는 균주들을 탐색한 결과, 10개의 균주가 선별되었다. 16S rRNA 유전자 염기서열을 결정하고 계통분석한 결과, 모두 Geobacillus 속으로 동정되었다. 균주들의 최적 성장온도는 $55^{\circ}C$와 $60^{\circ}C$, 최적 pH는 초기 pH가 6.0${\sim}$8.0일 때로 나타났으며, 염분 3%일 때를 기준으로 성장속도의 저해가 뚜렷하게 나타났다. 균주의 효소 활성도와 API 50 CHB kit에 의한 탄수화물 이용도를 바탕으로 균주의 생태학적 기능을 알아본 결과, G. stearothermophilus 균주들과 G. kaustophilus 균주들의 특성은 다른 종의 균주들과 명확히 구분되었으며, 나머지 균주들은 최적 성장환경의 생태학적 특징이 다양하게 나타나, 종별 구분과 정확히 일치하지는 않았다. 약산성 환경에서 최적 성장하는 G. stearothermophilus 균주들은 높은 단백질분해효소활성을 보이면서 다당류 분해와 단당류 이용도가 낮았고, 알칼리환경을 최적 서식지로 하는 G. kaustophilus 등은 이와 대조적으로 지질 분해 및 당류의 이용도가 높게 나타났다. 따라서, 수변 낙엽퇴적층에는 호열성 내성포자 형성 세균인 Geobacillus 속 균주들이 다양한 생태학적 지위를 가지며 퇴비화와 유사한 천이과정을 거치면서 수변 퇴적물질을 분해하는데 기여하는 것으로 보여진다.

• Journal of Plant Biotechnology
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• 제40권3호
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• pp.125-134
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• 2013

최근 연구에서 엽록체의 미지의 소기관으로 알려졌던 플라스토글로뷸이 지질 대사에서 중요한 역할을 함이 제시되고 있다. 애기장대 플라스토글로뷸의 프로테옴 단백질 분석은 플라스토글로뷸이 단순히 지질 저장 기관으로써의 기능 뿐아니라 지질 합성 대사에 능동적으로 관여하는 소기관임을 제시하고 있다. 애기장대 플라스토글로뷸에서 34개의 단백질이 발견되었다. 이들을 세 그룹으로 나누어 보면 구조단백질인 플라스토글로불린과 엽록체 대사에 관여하는 효소, 그리고 기능이 미확인된 단백질로 구분 된다. 이들 단백질 유전자의 돌연변이체와 리피도믹스 분석으로 이들 단백질의 기능 규명 연구가 필요하다. 토코페롤 합성의 마지막 단계에 관여하는 VTE1과 VTE4는 엽록체에서 각기 다른 위치에 존재하여 VTE1은 플라스토글로뷸에 존재하나 VTE4는 엽록체 내막에 존재한다. 이 같은 사실은 프레닐퀴논 대사물질이 엽록체 내에서 이동할 가능성을 시사한다. 플라스토글로뷸이 엽록체의 기능을 유지하는데 있어 필수적인지에 대한 유전학 연구가 앞으로 진행되어야 한다. 다양한 스트레스와 발달단계에 따른 플라스토글로뷸의 프로테옴 분석은 지질대사에서 중요한 기능을 하는 신규 단백질을 발견하는데 도움을 줄 것이다. 지금까지 결과로는 플라스토글로뷸은 프레릴퀴논 대사에 있어서 교차로 역할을 함을 제안하고 있다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2002년도 학술발표대회
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• pp.18-25
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• 2002

The pikromycin biosynthetic system in Streptomyces venezuleae is unique for its ability to produce two groups of antibiotics that include the 12-membered ring macrolides methymycin and neomethymycin, and the 14-membered ring macrolides narbomycin and pikromycin. The metabolic pathway also contains two post polyketide-modification enzymes, a glycosyltransferase and P450 hydroxylase that have unusually broad substrate specificities. In order to explore further the substrate flexibility of these enzymes a series of hybrid polyketide synthases were constructed and their metabolic products characterized. The plasmid-based replacement of the multifunctional protein subunits of the pikromycin PKS in S. venezuelae by the corresponding subunits from heterologous modular PKSs resulted in recombinant strains that produce both 12- and 14-membered ring macrolactones with predicted structural alterations. In all cases, novel macrolactones were produced and further modified by the DesVII glycosyltransferase and PikC hydroxylase leading to biologically active macrolide structures. These results demonstrate that hybrid PKSs in S. venezuelae can produce a multiplicity of new macrolactones that are modified further by the highly flexible DesVII glycosyltransferase and PikC hydroxylase tailoring enzymes. This work demonstrates the unique capacity of the S. venezuelae pikromycin pathway to expand the toolbox of combinatorial biosynthesis and to accelerate the creation of novel biologically active natural products. The polyketide backbone of rifamycin B is assembled through successive condensation and ${\beta}$-carbonyl processing of the extender units by the modular rifamycin PKS. The eighth module, in the RifD protein, contains nonfunctional DH domain and functional KR domain, which specify the reduction of the ${\beta}$-carbonyl group resulting in the C-21 bydroxyl of rifamycin B. A four amino acid substitution and one amino acid deletion were introduced in the putative NADPH binding motif in the proposed KR domain encoded by rifD. This strategy of mutation was based on the amino acid sequences of the corresponding motif of the KR domain of module 3 in the RifA protein, which is believed dysfunctional, so as to introduce a minimum alteration and retain the reading frame intact, yet ensure loss of function. The resulting strain produces linear polyketides, from tetraketide to octaketide, which are also produced by a rifD disrupted mutant as a consequence of premature termination of polyketide assembly. Much of the structural diversity within the polyketide superfamily of natural products is due to the ability of PKSs to vary the reduction level of every other alternate carbon atom in the backbone. Thus, the ability to introduce heterologous reductive segments such as ketoreductase (KR), dehydratase (DH), and enoylreductase (ER) into modules that naturally lack these activities would increase the power of the combinatorial biosynthetic toolbox. The dehydratase domain of module 7 of the rifamycin PKS, which is predicted to be nonfunctional in view of the sequence of the apparent active site, was replaced with its functional homolog from module 7 of rapamycin-producing polyketide synthase. The resulting mutant strain behaved like a rifC disrupted mutant, i.e., it accumulated the heptaketide intermediate and its precursors. This result points out a major difficulty we have encountered with all the Amycolatopsis mediterranei strain containing hybrid polyketide synthases: all the engineered strains prepared so far accumulate a plethora of products derived from the polyketide chain assembly intermediates as major products instead of just analogs of rifamycin B or its ansamycin precursors.

• Fisheries and Aquatic Sciences
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• 제23권1호
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• pp.1.1-1.14
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• 2020

Background: Dietary protein requirements are dependent on a variety of factors and water temperature is one of the most important abiotic factors affecting protein requirement of fish. This study was, therefore, conducted to investigate effects of water temperature on dietary protein requirement of fry Heteropneustes fossilis which has high demand in most of the Asian markets. Methods: Quadruplicate groups of 30 fish per treatment (2.97 ± 0.65 cm; 5.11 ± 0.34 g) were fed seven isoenergetic diets (17.9 kJ g^-1 gross energy; 14.99 kJ g^-1 digestible energy) containing dietary protein levels ranging from 28 to 52% at two water temperatures (18 and 26 ℃). Experimental diets were fed to apparent satiation as semi-moist cakes thrice daily at 17:00, 12:00, and 17:30 h for 12 weeks. For precise information, various growth parameters, protein deposition, hematological parameters, metabolic enzymes, and stress response were analyzed, and effects of water temperature on dietary protein requirement was recommended on the basis of response from above parameters. Results: Groups held at 26 ℃ attained best growth, feed conversion, and protein deposition at 44% dietary protein indicating that temperature affected dietary protein requirement for optimum growth of H. fossilis fry and protein requirement seems to be satisfied with 44% dietary protein. Interestingly, interactive effects of both dietary protein levels and temperature were not found (P > 0.05). Fish reared at 18 ℃ had comparatively higher values for aspartate and alanine transferases than those reared at 26 ℃ water temperature which exhibited normal physiological value for these enzymes indicating that body metabolism was normal at this temperature. Hematological parameters also followed same pattern. Furthermore, fish reared at 26 ℃ water temperature exhibited more resistant to thermal stress (P < 0.05). The 95% maximum plateau of protein deposition data using second-degree polynomial regression analyses exhibited dietary protein requirement of fry H. fossilis between 40.8 and 41.8% of diet at 26 ℃ water temperature. The recommended range of dietary protein level and protein/digestible energy ratio for fry H. fossilis is 40.8-41.8% and 27.21-27.88 mg protein kJ^-1 digestible energy, respectively. Conclusions: Information developed is of high significance for optimizing growth potential by making better utilization of nutrient at 26 ℃ and, to develop effective management strategies for mass culture of this highly preferred fish species.