• Journal of Microbiology and Biotechnology
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• 제22권9호
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• pp.1245-1252
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• 2012

Acinetobacter venetians V28 was isolated from the intestine of righteye flounder, Poecilopsetta plinthus caught in Vietnam seawater, and the esterase gene was cloned using a shotgun method. The amino acid sequence deduced from the nucleotide sequence (1,017 bp) corresponded to a protein of 338 amino acid residues with a molecular weight of 37,186. The esterase had 87% and 72% identities with the lipases of A. junii SH205 and A. calcoaceticus RUH2202, respectively. The esterase contained a putative leader sequence, as well as the conserved catalytic triad (Ser, His, Asp), consensus pentapeptide GXSXG, and oxyanion hole sequence (HG). The protein from the strain V28 was produced in both a soluble and an insoluble form when the Escherichia coli cells harboring the gene were cultured at $18^{\circ}C$. The maximal activity of the purified enzyme was observed at a temperature of $40^{\circ}C$ and pH 9.0 using p-NP-caprylate as substrate; however, relative activity still reached to 70% even at $5^{\circ}C$ with an activation energy of 3.36 kcal/mol, which indicated that it was a cold-adapted enzyme. The enzyme was a nonmetallo-protein and was active against p-nitrophenyl esters of $C_4$, $C_8$, and $C_{14}$. Remarkably, this enzyme retained much of its activity in the presence of commercial detergents and organic solvents. This cold-adapted esterase will be applicable as catalysts for reaction in the presence of organic solvents and detergents.

• 대한간호학회지
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• 제13권2호
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• pp.87-104
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• 1983

It has been well documented that animals exposed to cold show increased activity of thyroid gland. The calorigenic action of thyroid hormone has been demonstrated by a variety of in vivo and in vitro studies. According to Edelman et al., the thyroid thermogenesis is due to activation of energy consuming processes, especially the active sodium transport by the hormone in target tissues. If so, the increase in thyroid activity during cold exposure should induce increased capacity of sodium transport in target tissue and the change in tissue metabolism should be precisely correlated with the change in Na+_K+_ATPase activity of the tissue. This possibility was tested in the present study: in one series, changes in oxygen consumption and Na+_K+_-ATPase activity of liver preparations were measured in rats as a function of thyroid status, in order to establish the effect of thyroid hormone on the tissue respiration and enzyme system in another series, the effect of cold stimulus on the serum thyroid hormone level, hepatic tissue oxygen consumption and Na+_K+_ATPase activity in rats. The results obtained are as follows: 1. The Na+_dependent oxygen consumption of liver slices, the oxygen consumption of liver mitochondria and the Na+_K+_ATPase activity of liver preparations were significantly inhibited in hypothyroidism and activated in hyperthyroidism. Kinetic analysis indicated that the Vmax. of Na+_K+_ATPase was decreased in hypothyroidism and increased in hyperth)'roidism. 2. In cold exposed rats, the serum triiodothyronine (T₃) level increased rapidly during the initial one day of cold exposure, then declined slowly to the control level after two weeks. The serum thyroxine (T₄) level decreased gradually throughout the cold exposure. Accordingly the T₃/T₄ratio increased. The mitochondrial oxygen consumption and the Na+_dependent oxygen consumption of liver slices increased during the first two days and then remained unchanged thereafter The activity of the Na+_K+_ATPase in liver preparations increased during cold exposure with a time course similar to that of oxygen consumption. Kinetic analysis indicated that the Vmax. of Na+_K+_ATPase increased. 3. Once the animal was adapted to cold, induction of hypothyroidism did not significantly alter the hepatic oxygen consumption and Na+_K+_ATPase activity. These results indicate that: 1) thyroid hormone increases capacities of mitochondrial respiration and active sodium transport in target tissues such as liver; 2) the increased T₃level during the initial period of cold exposure facilitates biosynthesis of Na+_K+_ATPase and mitochondrial enzymes for oxidative phosphorylation, leading to enhanced production and utilization of ATP, hence heat production.

• 미생물학회지
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• 제54권1호
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• pp.60-68
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• 2018

남극 해양세균 Pseudoalteromonas arctica PAMC 21717로부터 저온활성 alkaline protease (Pro21717)를 부분정제하였다. Pro21717 효소 추출액은 skim milk를 포함하는 zymogram gel 상에서 약 37 kDa (낮은 활성)과 74 kDa (높은 활성) 위치에서 두 개의 뚜렷한 투명밴드(clear zone)를 형성하였다. 단백질 분해활성을 나타내는 두 개의 효소단백질은 동일한 N-말단 아미노산 서열을 가지고 있었으며, 하나의 유전자에서 발현된 미성숙 단백질(precursor)이 37 kDa 크기의 단백질분해효소로 성숙화과정을 거친 후 74 kDa 크기로 이량체화됨으로써 좀 더 높은 활성을 가지는 것으로 판단된다. Pro21717은 $0-40^{\circ}C$ (최고활성 온도 $40^{\circ}C$) 온도 범위에서 단백질분해활성을 나타내었고 pH 5.0-10.0 (최적 pH 9.0) 범위에서 효소활성을 유지하였다. 주목할만한 특성으로써, Pro21717은 $40^{\circ}C$에서의 최고 효소활성(100%) 대비, $0^{\circ}C$와 $10^{\circ}C$에서 각각 30%와 45%의 높은 저온활성을 나타내었다. 또한 다양한 합성 펩타이드류에 대해 분해활성을 나타내는 Pro21717은 $Cu^{2+}$에 의해 활성이 증가하였으며, 시판용 세탁세제(commercial detergent formulation)에 포함되어 있는 다양한 종류의 계면활성제, 화학성분, 금속이온에 의해 활성이 감소되지 않았다. 전반적으로 저온활성 Pro21717은 글로벌 상업용효소 생산회사 Novozymes이 시판하고 있는 중온성 효소 Subtilisin Carlsberg (trademark Alcalase)에 버금가는 유용한 효소학적 특성이 있는 동시에 상대적으로 더 높은 저온활성을 보여주고 있다. 위의 실험결과들은, Pro21717은 $15^{\circ}C$ 이하의 차가운 수돗물에서도 세척력을 유지하는 새로운 세탁세제 효소첨가제로서의 개발 가능성을 보여주고 있다.

• Journal of Microbiology and Biotechnology
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• 제29권2호
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• pp.244-255
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• 2019

Xylose isomerase (XI; E.C. 5.3.1.5) catalyzes the isomerization of xylose to xylulose, which can be used to produce bioethanol through fermentation. Therefore, XI has recently gained attention as a key catalyst in the bioenergy industry. Here, we identified, purified, and characterized a XI (PbXI) from the psychrophilic soil microorganism, Paenibacillus sp. R4. Surprisingly, activity assay results showed that PbXI is not a cold-active enzyme, but displays optimal activity at $60^{\circ}C$. We solved the crystal structure of PbXI at $1.94-{\AA}$ resolution to investigate the origin of its thermostability. The PbXI structure shows a $({\beta}/{\alpha})_8$-barrel fold with tight tetrameric interactions and it has three divalent metal ions (CaI, CaII, and CaIII). Two metal ions (CaI and CaII) located in the active site are known to be involved in the enzymatic reaction. The third metal ion (CaIII), located near the ${\beta}4-{\alpha}6$ loop region, was newly identified and is thought to be important for the stability of PbXI. Compared with previously determined thermostable and mesophilic XI structures, the ${\beta}1-{\alpha}2$ loop structures near the substrate binding pocket of PbXI were remarkably different. Site-directed mutagenesis studies suggested that the flexible ${\beta}1-{\alpha}2$ loop region is essential for PbXI activity. Our findings provide valuable insights that can be applied in protein engineering to generate low-temperature purpose-specific XI enzymes.

• 청정기술
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• 제22권3호
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• pp.175-180
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• 2016

본 연구에서는, 저온 및 약산성 조건에서 높은 활성을 보이는 티로시나아제인 tyrosinase-CNK의 반응 안정성을 조사하였다. Tyrosinase-CNK는 지금까지 알려진 중온성(mesophilic) 및 호열성(thermophilic) 환경 유래의 티로시나아제 보다는 열 안정성이 낮았으나 0 ℃에서 효소 안정성이 매우 뛰어났고, 반복적인 동결-해동(freeze-thaw) 과정에서도 효소 활성을 안정적으로 유지하였다. 또한, 물과 ethanol 및 acetonitrile이 혼합된 유기용매 환경에서 초기 상대 활성 값의 변화가 관찰되었으나 유기용매 농도의 증가로 인한 추가적인 활성 저하를 유발하지 않고 활성을 일정하게 유지하였다. 한편, 효소 반응의 염(salt)에 대한 저해는 chaotropic 특성이 많이 나타나는 염일수록 적게 나타났다. 결과적으로, tyrosinase-CNK는 통상의 티로시나아제를 이용하여 반응을 수행하기 어려운 환경에서도 원하지 않는 반응을 억제하고 효소 불활성화를 최소화면서 반응을 촉매할 것으로 기대된다.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1085-1091
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• 2009

A phytase with high activity at low temperatures has great potential for feed applications, especially in aquaculture. Therefore, this study used a degenerate PCR and TAIL PCR to clone a phytase gene from Erwinia carotovora var. carotovota, the cause of soft rot of vegetables in the ground or during cold storage. The full-length 2.5-kb fragment included an open reading frame of 1,302 bp and encoded a putative phytase of 45.3 kDa with a 50% amino acid identity to the Klebsiella pneumoniae phytase. The phytase contained the active site RHGXRXP and HD sequence motifs that are typical of histidine acid phosphatases. The enzyme was expressed in Escherichia coli, purified, and displayed the following characteristics: a high catalytic activity at low temperatures (retaining over 24% activity at $5^{\circ}C$) and remarkably thermal lability (losing >96% activity after incubation at $60^{\circ}C$ for 2 min). The optimal phytase activity occurred at pH 5.5 and ${\sim}49^{\circ}C$, and the enzyme activity rapidly decreased above $40^{\circ}C$. When compared with mesophilic counterparts, the phytase not only exhibited a high activity at a low temperature, but also had a low $K_m$ and high $k_{cat}$. These temperature characteristics and kinetic parameters are consistent with low-temperature-active enzymes. To our knowledge, this would appear to be the first report of a low-temperature-active phytase and its heterogeneous expression.

• 한국미생물·생명공학회지
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• 제23권5호
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• pp.550-555
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• 1995

A strain of Pseudomonas sp. isolated from soil was shown to produce a high level of extracellular endo-inulinase. In this work, the endo-inulinase gene (inu1) of the bacterial strain was cloned into the plasmid pBR322 by using EcoRI restriction endonuclease and E. coli HB101 as a host strain. One out of 7, 000 transformants obtained from the above cloning experiment formed a clear zone around its colony on the selective medium supplemented with 2.0% inulin after a prolonged incubation at 37$\circ$C and subsequent cold shock treatment. The functional clone was found to carry a recombinant plasmid (pKMG50) with a 3.7 kb genomic insert containing the genetic information for the inulinase activity. The inulinase from E. coli HB101/pKMG50 was proved to be an endo-acting enzyme and produced constitutively in the recombinant E. coli cells. Zymogram of the enzyme from the recombinant cells with inulin substrate indicated that the molecular mass of the active protein was 190 Kd, while that of the endo-inulinase from the Pseudomonas strain was 170 Kd. This size discrepancy suggested that the inulinase from the recombinant E. coli HB101 cells might be the initial product of translation, not the mature form produced in the strain of Pseudomonas sp..

• Journal of Microbiology
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• 제41권1호
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• pp.22-27
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• 2003

A lipase from Aeromonas sp. LPB 4, a psychrotophile isolated from a sea sediment was purified and characterized. The lipase was purified 53.5 fold to a homogeneous state by acetone precipitation and QAE sephadex column chromatography and its molecular weight was determined to be 50 kDa by SDS-PAGE. The enzyme exhibited maximum activity at 10$^{\circ}C$ and was stable at temperatures lower than 50$^{\circ}C$. This lipase favored substrates containing medium carbon chain of acyl group, while too low and high carbon chain decreased its activity. The lipolytic activity of purified lipase was slightly increased by the addition of 0.1% detergent, but decreased by 1% of detergent. Butanol severely decreased the lipase activity while methanol increased the activity about 15%.

• KSBB Journal
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• 제31권2호
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• pp.126-134
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• 2016

To examine the possibility of using Musa sapientum L. (Banana) leaf extract as a cosmetic raw material, banana leaves grown in Jeju Island were extracted with 70% ethanol. Polysaccharides present in banana leaf extract were discarded by precipitation with cold ethanol. Polysaccharide-discarded banana leaf extract promoted procollagen and COL1A1 gene expression, but inhibited matrix metalloproteinase (MMP)-1 and MMP-2 gene expression in human skin fibroblasts when examined by real-time reverse-transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The active compound in banana leaves was identified by fractionation with various solvents. The chloroform fraction showed the highest anti-wrinkle efficacy and the active compound of chloroform fraction was identified as corosolic acid by NMR, FT-IR, EA, and HPLC-MS. In addition, banana leaf extract showed anti-oxidative efficacy with an IC50 value of 67.91 ppm, as determined by DPPH free radical scavenging assay. Finally, the anti-wrinkle efficacy of banana leaf extract-containing cream was confirmed by clinical tests. Based on these results, banana leaves could have an application as a cosmetic raw material with anti-wrinkle efficacy.

• 대한한방내과학회지
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• 제41권4호
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• pp.553-562
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• 2020

Objective: To investigate the vasodilatory effect of Sipjeondaebo-tang by inhibiting RhoA activity in vascular cells during cold exposure. Methods: Human vascular endothelial cells and pericytes were pretreated with Sipjeondaebo-tang for 30 min, followed by incubation at 37 ℃ (control) or 25 ℃ (cold exposure) for 30 min. Activation of endothelin-1-mediated RhoA in pericytes was assessed by pretreating the cells with Sipjeondaebo-tang for 30 min, followed by incubation with endothelin-1 at 37 ℃ for 30 min. Western blotting was performed to measure the expression of active RhoA. Endothelin-1 and nitric oxide release from endothelial cells was examined with enzyme-linked immunosorbent assay kits. The formation of stress fibers and focal adhesion complexes was analyzed by immunocytochemistry. Results: Cold treatment activated RhoA in both pericytes and vascular endothelial cells, whereas Sipjeondaebo-tang treatment inhibited this activation. Sipjeondaebo-tang treatment also reversed the cold-mediated production of endothelin-1 and nitric oxide. Cold exposure promoted the formation of stress fibers and focal adhesion complexes by increasing the expression of phospho-focal adhesion complex kinase, whereas Sipjeondaebo-tang treatment suppressed this response. Conclusions: These findings suggested that Sipjeondaebo-tang inhibits cold-induced RhoA activation and its related pathway components, including endothelin-1 and nitric oxide, in vascular cells. Therefore, Sipjeondaebo-tang could be beneficial for the treatment of Raynaud's phenomenon.