• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2087-2097
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• 2016

Most cold-adapted enzymes possess higher $K_m$ and $k_{cat}$ values than those of their mesophilic counterparts to maximize the reaction rate. This characteristic is often ascribed to a high structural flexibility and improved dynamics in the active site. However, this may be less convincing to cold-adapted metabolic enzymes, which work at substrate concentrations near $K_m$. In this respect, cold adaptation of a shikimate kinase (SK) in the shikimate pathway from psychrophilic Colwellia psychrerythraea (CpSK) was characterized by comparing it with a mesophilic Escherichia coli homolog (EcSK). The optimum temperatures for CpSK and EcSK activity were approximately $30^{\circ}C$ and $40^{\circ}C$, respectively. The melting points were $33^{\circ}C$ and $45^{\circ}C$ for CpSK and EcSK, respectively. The ${\Delta}G_{H_2O}$ (denaturation in the absence of denaturing agent) values were 3.94 and 5.74 kcal/mol for CpSK and EcSK, respectively. These results indicated that CpSK was a cold-adapted enzyme. However, contrary to typical kinetic data, CpSK had a lower $K_m$ for its substrate shikimate than most mesophilic SKs, and the $k_{cat}$ was not increased. This observation suggested that CpSK may have evolved to exhibit increased substrate affinity at low intracellular concentrations of shikimate in the cold environment. Sequence analysis and homology modeling also showed that some important salt bridges were lost in CpSK, and higher Arg residues around critical Arg 140 seemed to increase flexibility for catalysis. Taken together, these data demonstrate that CpSK exhibits characteristics of cold adaptation with unusual kinetic parameters, which may provide important insights into the cold adaptation of metabolic enzymes.

• 한국식품영양과학회지
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• 제45권9호
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• pp.1302-1309
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• 2016

N-Nitrosodimethylamine(NDMA)은 dimethylamine(DMA)과 아질산염이 반응하여 생성되고 김치의 재료 중 하나인 젓갈은 다량의 DMA를 함유하고 있다. 본 연구에서는 김치저장 중 NDMA와 그 전구물질 함량 변화에 젓갈의 종류와 양의 영향력에 대해 알아보았다. 젓갈 시료 23건 모두에서 NDMA가 검출되었고 새우젓 9건의 DMA 함량 범위는 16.5~58.9 mg/kg이고, 평균은 30.9 mg/kg이었다. 7건의 멸치액젓에 함유된 DMA 범위는 21.7~44.4 mg/kg이고, 평균은 34.5 mg/kg이었다. 김치는 5그룹으로 나누었다. 즉 멸치액젓과 새우젓을 넣지 않은 김치(대조군), 적은 양의 멸치액젓을 넣은 김치(AK1), 많은 양의 멸치액젓을 넣은 김치(AK2), 적은 양의 새우젓을 넣은 김치(SK1), 그리고 많은 양의 새우젓을 넣은 김치(SK2)로 나누었다. 김치 저장기간 동안 SK2가 SK1보다 DMA 함량이 높았고, 김치 저장 10일 후 AK2가 AK1보다 DMA 함량이 높았다. AK1과 SK1에 함유한 아질산염 함량은 김치 저장 20일에 AK2와 SK2에 함유된 아질산염 함량보다 높았다. 김치 저장 0과 10일에 NDMA 함량이 SK2 내에서 SK1 내의 그것보다 현저하게 높았고, 저장 0일에 AK2 내 NDMA 함량이 AK1 내 그것보다 현저하게 높았다. DMA와 NDMA에 대한 젓갈의 양과 종류에 대한 영향은 저장 초기에는 뚜렷하였으나 20일 동안 저장한 김치에서는 감소하였다. 이들 결과는 젓갈의 함량과 종류가 김치 내 NDMA 형성에 영향을 미친다는 것을 제안하였다.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.143.2-144
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• 2003

Joins (SKI 306X) is now clinically used for the treatment of osteoarthritis (OA). In previous reports, Joins a natural herbal product extracted from three herbs Clematis Radix. Trichosanthes Radix and Prunella Flos, was shown to have good analgesic and anti-inflammatory effects in several in vivo models. e.g., acetic acid-induced pain, carrageenan-induced paw edema and adjuvant-induced arthritis. (omitted)

• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.919-923
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• 2004

The sk10 isolated from kimchi was identified as W. kimchii on the basis of l6s-rDNA sequencing. Studies were made to analyze the metabolic flux shift of the sk10 on glucose under aerobic growth conditions. The sk10 produced 38.2 mM acetate, 16.3 mM ethanol, and 33.2 mM lactate under aerobic conditions, but 2.4 mM acetate, 48.0 mM ethanol, and 44.1 mM lactate under anaerobic conditions. The NADH peroxidase (NADH-dependent hydrogen peroxidase) activity of sk10 grown under aerobic conditions was 11 times higher than that under anaerobic conditions. Under the low ratio of $NADH/NAD^+$, the metabolic flux toward lactate and ethanol was shifted to the flux through acetate kinase without NADH oxidation. The kinds of enzymes and metabolites of sk10 were close to those in the pathway of Leuconostoc sp., but the metabolites produced under aerobic growth conditions were different from those of Leuconostoc sp. The stoichiometric balance calculated using the concentrations of metabolites and substrate was about 97%, coincident with the theoretical values under both aerobic and anaerobic conditions. From these results, it was concluded that the metabolic flux of W. kimchii sk10 was partially shifted from lactate and ethanol to acetate under aerobic conditions only.

• Archives of Pharmacal Research
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• 제19권4호
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• pp.261-263
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• 1996

SK-302B, an antibiotic purified from soil Streptomyces sp. 302, was structurally identified as echinomycin (C/sub 50/H/sub 66/N/sub 11/S/sub 2/). In the present experiment, the possibility of SK-302B as an anticolon cancer agent was investigated by using chemosensitivity system (MTT assay, clonogenic assay). Treatment of SK-302B on various colon cancer cell lines resulted in a significant cytotoxicity and tumor colony formation inhibition. These studies showed that SK-302B had a potent inhibition on colon cancer cells.

• Molecules and Cells
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• 제27권5호
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• pp.601-608
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• 2009

The 2-deoxystreptamine and paromamine are two key intermediates in kanamycin biosynthesis. In the present study, pSK-2 and pSK-7 recombinant plasmids were constructed with two combinations of genes: kanABK, and kanABKF and kacA respectively from kanamycin producer Streptomyces kanamyceticus ATCC12853. These plasmids were heterologously expressed into Streptomyces lividans TK24 independently and generated two recombinant strains named S. lividans SK-2/SL and S. lividans SK-7/SL, respectively. ESI/ MS and ESI-LC/MS analysis of the metabolite from S. lividans SK-2/SL showed that the compound had a molecular mass of 163 $[M+H]^+$, which corresponds to that of 2-deoxystreptamine. ESI/MS and MS/MS analysis of metabolites from S. lividans SK-7/SL demonstrated the production of paromamine with a molecular mass of $324[M+H]^+$. In this study, we report the production of paromamine in a heterologous host for the first time. This study will evoke to explore complete biosynthetic pathways of kanamycin and related aminoglycoside antibiotics.

• 한국미생물·생명공학회지
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• 제49권4호
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• pp.594-602
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• 2021

The NLRP3 (nucleotide-binding domain, leucine-rich repeat family pyrin domain containing 3) inflammasome plays an important role in the initiation of inflammatory responses, through the recognition of pathogen-associated molecular patterns and tumor progression, including tumor growth and metastasis. In this study, we examined the effects of defective NLRP3 on the growth, migration, and invasiveness of hepatocellular carcinoma (HCC) SK-Hep1 cell. First, HCC SK-Hep1 cells were transfected with human NLRP3 targeting LentiCRISPRv2 vector using the CRISPR-Cas9 system, and NLRP3 deficiency was confirmed by RT-qPCR and western blotting. NLRP3 deficient SK-Hep1 cells showed delayed cell growth and decreased protein expression of PI3K, p-AKT, and pNF-κB when compared to NLRP3 complete SK-Hep1 cells. In addition, NLRP3 deficiency arrested the cell cycle at G1 phase through an increase in p21 and a reduction in CDK6. NLRP3 deficient SK-Hep1 cells also showed significantly delayed cell migration, invasion, and wound healing. The expression of epithelial-mesenchymal transition signaling molecules, such as N-cadherin and MMP-9, was found to be dramatically decreased in NLRP3 deficient SK-Hep1 cells compared to NLRP3 complete SK-Hep1 cells.

• Mass Spectrometry Letters
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• 제2권4호
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• pp.88-91
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• 2011

The pharmacokinetic properties of S-amlodipine were studied using racemic amlodipine and single S-enantiomer (SK310) administration to rats. Plasma levels of the drug were determined using chiral liquid chromatography coupled with tandem mass spectrometry following solid phase extraction. The stereospecific analysis of amlodipine was performed on an ${\alpha}$-acid glycoprotein (AGP) column using a mobile phase comprising 10 mM ammonium acetate (pH 4.0) and propanol at a flow rate of 0.2 mL/min. This method was used to perform a comparative study of the pharmacokinetics of amlodipine and SK310. The results revealed that the pharmacokinetic profile of S-amlodipine after the administration of SK310 was comparable to that following the administration of the racemic mixture.

• Parasites, Hosts and Diseases
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• 제39권2호
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• pp.143-150
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• 2001

The present study was designed to investigate polymorphism in Duffy binding protein (DBP) gene of Plasmodium vivax isolates of Korea. Thirty samples were obtained from P. vivax patients in Yonchon-gun, Kyonggi-do in 1998. The PCR products of the samples were subjected to sequencing and hybridization analyses of the regions II and IV of P. vivax DBP gene. Two genotypes, SK-1 and SK-2, were identified on the basis of amino acid substitution and deletion. The genotype of 10 isolates was SK-1 and that of 20 isolates was SK-2. Most of the predicted amino acids in the region ll of DBP gene were conserved between the Korean isolates and Belem strain except for 4-5 amino acid substitutions. In the region W of DBP, a 6-bp insert that was shown in the Sal-1 allele type was found in SK-1, and a 27-bp insert that was shown in the Papua New Guinea allele type was found in SK-2. In conclusion, the present findings suggest that two genotypes of P. vivax coexist in the endemic area of Korea.

• The Korean Journal of Physiology and Pharmacology
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• 제13권3호
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• pp.139-145
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• 2009

The purpose of this study was to evaluate the effects of the water extract of Samultang (SMT), a Chinese herb, on apoptotic cell death by $H_2O_2$-induced oxidative stress in SK-N-M C cells. A nuclear fragmentation was observed via fluorescence imaging 12 h after exposure to 30 ${\mu}M$ $H_2O_2$ and DNA laddering was detected via agarose electrophoresis gel. In addition, increases in sub-G1 phase and cleavage of the PARP protein were observed. However, treatment with SMT for 2 h prior to $H_2O_2$ exposure significantly reduced apoptotic cell death induced by incubation with 30 ${\mu}M$ $H_2O_2$ in SK-N-MC cells. Pre-incubation with water extract of SMT for 2 h prevented the $H_2O_2$-induced decrease in mitochondrial transmembrane potential. SMT also attenuated the increase in caspase-3 activity and the breakdown of PARP protein caused by $H_2O_2$-induced oxidative stress. These results suggest that the water extract of SMT provides inhibition of apoptotic cell death against oxidative injury in SK-N-MC cells.