• 한국식품영양과학회지
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• 제37권11호
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• pp.1507-1514
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• 2008

본 연구에서는 산업적으로 사용될 수 있는 안정하고 활성이 높은 cholesterol oxidase를 생산하는 균주를 얻기 위해 토양 미생물로부터 균주를 선별하였다. 선별된 균주에 대하여 세포외 효소 활성을 측정한 결과 BEN 115로 명명한 균주가 가장 높은 효소 활성도를 나타내었다. 이 균주는 형태학적, 생리학적 특성과 배양형태 및 G＋C 함량을 분석한 결과 Nocardia속으로 확인되었다. 최적 효소 생산 조건을 조사한 결과 기존 yeast malt extract broth 조성인 0.4% yeast extract, 0.4% glucose, 1% malt extract에서 가장 높은 활성을 나타냈다. 본 균주에서 생산된 extracellular cholesterol oxidase는 SDS-PAGE와 Western blot 결과 분자량이 55, 57 kDa인 두 종류의 효소가 존재하는 것으로 나타났다. BEN 115에 대한 효소학적 특성을 연구한 결과 온도 안정성은 $55^{\circ}C$까지 효소 활성이 유지되었고, pH 안정성은 pH $3.5{\sim}9.5$의 범위까지 안정한 것으로 나타났으며 최적 온도와 최적 pH는 각각 35oC와 pH 5.5인 것으로 나타났다. 또한 detergent(Triton X-100, Triton X-114 그리고 Tween 80) 첨가 시 효소 활성이 첨가하지 않은 대조군보다 약 $1.6{\sim}2.0$배 증가하는 것으로 나타났다. Campesterol, sitosterol 그리고 stigmasterol에 대한 기질 특이성은 cholesterol(100%)과 상대적으로 비교 시 각각 50%, 50% 그리고 27%의 기질 특이성을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제20권7호
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• pp.1101-1106
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• 2010

Pulsed electric field (PEF) of 1Hz, 1.5 kV, and 1ms increased the activities of catalase and inulinase over the whole range of applied Se concentrations compared with the non-treated cultures. A significant effect of selenium concentration (in the range of 5-14 ${\mu}g/ml$) on both intra- and extracellular enzyme activities was noted. At a Se concentration of 10 ${\mu}g/ml$, the activities of intra- and extracellular inulinases and extracellular catalase in the PEF-treated cultures reached the maximum of 71 U/g d.m., 46 U/g d.m., and approx. 8 U/ml, respectively. The maximum activity of intracellular catalase of approx. 6 U/ml (with and without PEF) was recorded at 5 ${\mu}g$ Se/ml. Further increasing of selenium concentration caused a decrease in the activity of the enzymes.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권5호
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• pp.359-362
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• 2001

The production of an extracellular polysaccharide, EPS-R, from the marine bacterium Hahella chejuensis was investigated at various aeration rates in a batch culture. Higher aeration rate resulted in enhanced EPS production and increased the viscosity of the culture broth. At an aeration rate of 1.5 vvm, EPS-R (12.2 g/L) was obtained with a yield (Y$\_$p/s) of 0.6 from the STN medium after 72 h of cultivation. The H. chejuensis cells changed rod morphology to a short-rod form in the stationary growth phase.

• 한국임상수의학회지
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• 제37권4호
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• pp.213-216
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• 2020

Two cats were presented to the Dana Animal Hospital Eye Center and were diagnosed with corneal sequestrum through full ophthalmic examination. After lamellar keratectomy using a reusable corneal trephine blade and a crescent microsurgical knife, porcine urinary bladder submucosa extracellular matrix (UBM, ACeLL Vet^® corneal disc) was applied to the corneal defects. In both cases, no corneal sequestrum recurrences were observed until 119 days and 253 days after the surgery, respectively. Porcine UBM could be recommended as a surgical scaffold for treatment of corneal sequestrum in cats.

• The Korean Journal of Ecology
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• 제18권3호
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• pp.409-418
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• 1995

As a part of studying the function and structure of the mudflat environment of the Yellow Sea, seawater samples in the overlying waters of sediment near Daesan were collected every hour on March 29 (spring tides) and on April 5 (neap tides), 1995 to study the diurnal distribution of aerobic saprophytic bacteria and their extracellular enzyme activities. The diurnal distribution of aerobic saprophytic bacteria ranged from 1.0 X $10^{2}$ to 7.07 X $10^{3}$ cfu /ml at spring tides and from 1.0 X $10^{2}$ to 8.3 X $10^{3}$ cfu /ml at neap tides. The diurnal variations of aerobic saprophytes at the suface waters were greater than those of middle and bottom waters. However, th diurnal fluctuation of saprophyte numbers at spring tides showed no significant difference compared with that at neap tides. The numbers of three physiological groups of aerobic hacteria (proteolytic, lipolytic and amylolytic bacteria) at the surface waters during spring and neap tides were lower than those at the middles and bottom waters. The diurnal variations of five extracellular enzyme activities at the surface waters during the survey period showed lower values than those at the middle and botton waters. Among the measured extracellular enzyme activities, phosphatase showed the highest. However, the activities of amylase, chitinase and cellulase showed a similar tendency.

• Journal of Microbiology
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• 제44권4호
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• pp.447-452
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• 2006

The murine ecotropic retroviral receptor has been demonstrated to function as a mouse cationic amino acid transporter 1(mCAT1), and is comprised of multiple membranespanning domains. Feral mouse (Mus dunni) cells are not susceptible to infection by the ecotropic Moloney murine leukemia virus (MoMLV), although they can be infected by other ecotropic murine leukemia viruses, including Friend MLV and Rauscher MLV. The relative inability of MoMLV to replicate in M. dunni cells has been attributed to two amino acids $(V_{214}\;and\;G_{236})$ located within the third extracellular loop of the M. dunni CAT1 receptor (dCAT1). Via the exchange of the third extracellular loop of the mCAT1 cDNA encoding receptor from the permissive mouse and the corresponding portion of cDNA encoding for the nonpermissive M. dunni receptor, we have identified the most critical amino acid residue, which is a glycine located at position 236 within the third extracellular loop of dCAT1. We also attempted to determine the role of the third extracellular loop of the M. dunni CAT1 receptor with regard to the formation of the syncytium. The relationship between dCAT1 and virus-induced syncytia was suggested initially by our previous identification of two MLV isolates (S82F in Moloney and S84A in Friend MLV), both of which are uniquely cytopathic in M. dunni cells. In an attempt to determine the relationship existing between dCAT1 and the virally-induced syncytia, we infected 293-dCAT1 or chimeric dCAT1 cells with the S82F pseudotype virus. The S82F pseudotype virus did not induce the formation of syncytia, but did show increased susceptibility to 293 cells expressing dCATl. The results of our study indicate that S82F-induced syncytium formation may be the result of cell-cell fusion, but not virus-cell fusion.

• 약학회지
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• 제56권2호
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• pp.108-115
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• 2012

The hyperpolarization-activated current ($I_h$) is an inward cation current activated by hyperpolarization of the membrane potential and plays a role as an important modulator of action potential firing frequency in many excitable cells. In the present study we investigated the effects of extracellular divalent cations on $I_h$ in dorsal root ganglion (DRG) neurons using whole-cell voltage clamp technique. $I_h$ was slightly increased in $Ca^{2+}$-free bath solution. BAPTA-AM did not change the amplitudes of $I_h$. Amplitudes of $I_h$ were decreased by $Ca^{2+}$, $Mg^{2+}$ and $Ba^{2+}$ dose-dependently and voltage-independently. Inhibition magnitudes of $I_h$ by external divalent cations were partly reversed by the concomitant increase of extracellular $K^+$ concentration. Reversal potential of $I_h$ was significantly shifted by $Ba^{2+}$ and $V_{1/2}$ was significantly affected by the changes of extracellular $Ca^{2+}$ concentrations. These results suggest that $I_h$ is inhibited by extracellular divalent cations ($Ca^{2+}$, $Mg^{2+}$ and $Ba^{2+}$) by interfering ion influxes in cultured rat DRG neurons.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.78-89
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• 2000

Protein secretion in filamentous fungi has been shown to be restricted to actively growing hyphal tips. To determine whether an increase in the amount of growing surface area of a fungus can lead to an increase in the amount of protein secretion, we examined secretion in a temperature-sensitive Neurospora crassa mcb mutant that shows a loss of growth polarity when incubated at restrictive-temperature. Incubation of the mcb mutant at restrictive-temperature results in a three- to five-fold increase in the level of extracellular protein and a 20- fold increase in carboxymethyl cellulase activity relative to a wild-type strain. A mutation in the cr-l gene has been shown previously to suppress the apolar growth phenotype of the mcb mutant, and we find that the level of extracellular protein produced by a mcb; cr-l double mutant was reduced to that of the wild-type control. Immunolocalization of a secreted endoglucanase revealed that proteins are secreted mainly at hyphal tips in hyphae exhibiting polar growth and over the entire surface area of bulbous regions of hyphae that are produced following a shift of the mcb mutant to restrictive-temperature. These results support the hypothesis that secretion of extracellular protein by a filamentous fungus can be significantly increased by mutations that alter growth polarity.

• 대한수의학회지
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• 제30권2호
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• pp.187-192
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• 1990

돼지로부터 분리한 Staphylococcus hyicus subsp hyicus 489주의 protein A 존재여부와 함량을 indirect hemagglutination 및 enzyme-linked immunosorbent assay(ELISA)법으로 조사하였다. Indirect hemagglutination text에 의하여 cell-bound protein A 및 extracellular protein A 보유균은 489주 중 각각 87.7% 및 36.0%로 나타났다. ELISA법에 의한 이들 균의 protein A함량 측정에서 전균주의 extracellular protein A는 1ng/ml미만이었으며, cell-bound protein A함량은 대부분의 균주에서 1ng/ml 미만이었고 11주가 25~108ng/ml 수준이었다.

• KSBB Journal
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• 제11권1호
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• pp.37-45
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• 1996

한국의 남해안에서 한천 분해능이 뛰어난 해양 미 생물을 분리하여 통정한 결과 Pseudomonas 속으로 판명되었으며, 본 연구에서는 이 균을 Halophilic P Pseudomonas sp. W7이라 명영하였다. 이 균주는 호염성 세균으로, 한천의 존재 하에서 높은 효소활성 을 가지는 extracellular agarase를 생산해 내었다. 이 extracellular agarase를 DEAE-Cellulose ani- on exchange chromatography와 gel filtration을 통해 정제하였으며, 정제된 agarase는 SDS-PAGE 를 통해 약 89KDa의 분자량을 지니는 single protein band염을 확인하였다. 한편 agarase의 대량생 산을 위하여 host cell Eo coli JM83과 vector pUC19를 이용하여 gene cloning을 행하였다. Pseudomonas sp. W7의 chromosomal DNA가 삽 입 된 균주 중에 서 agarase activity를 나타내는 E. coli JM83/pSWl과 Eo coli JM83/pSW3를 선멸하 였으며, 전기영통 실험결과 이들은 각각 307Kb, 3.0 K Kb의 chromosomal 단편을 지니고 있음을 확인하였 다. 또한 agarase 유전자가 압입된 변이 균주(B)는 inclusion body 형태의 interacellular agarase를 세포 내에 축적하고 있음이 확인되었다.