• 산업식품공학
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• 제15권4호
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• pp.289-296
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• 2011

Twenty four fractions by solvent extraction and/or acid precipitation from fruit body and culture broth of Inonotus obliquus were prepared, and their inhibitory effect against acetylcholinesterase (AChE) was investigated. Among these fractions, acid (1 M HCl) precipitates from cell-free culture broth and fruit body exhibited the highest inhibitory effect on AChE in vitro. Acid precipitates inhibited AChE activity in a concentration-dependant manner and $IC_{50}$ values of both acid precipitates were 0.53 mg/mL. The inhibition pattern was general non-competitive inhibition. The energetic parameters were also determined by dual substrate/temperature design. Both acid precipitates increased the values of Ea, ${\Delta}H,/;{\Delta}G$ and ${\Delta}H^{\ast}$ decreasing the value of ${\Delta}S$ for AChE. The results implied that the acid precipitates from I. obliquus increased the thermodynamic barrier, leading to the breakdown of ES complex and the formation of products as inhibitory mechanism.

• Journal of Microbiology and Biotechnology
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• 제23권8호
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• pp.1099-1106
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• 2013

Tuta absoluta (Povolny, 1994) is a devastating moth to the Solanaceae plants. It is a challenging pest to control, especially on tomatoes. In this work, we studied the entomopathogenic activity of the Cry-forming ${\delta}$-endotoxins produced by Bacillus thuringiensis strain KS and B. thuringiensis kurstaki reference strain HD1 against T. absoluta. These strains carried the cry2, cry1Ab, cry1Aa/cry1Ac, and cry1I genes, and KS also carried a cry1C gene. The ${\delta}$-endotoxins of KS were approximately twofold more toxic against the third instar larvae than those of HD1, as they showed lower 50% and 90% lethal concentrations (0.80 and 2.70 ${\mu}g/cm^2$ (${\delta}$-endotoxins/tomato leaf)) compared with those of HD1 (1.70 and 4.50 ${\mu}g/cm^2$) (p < 0.05). Additionally, the larvae protease extract showed at least six caseinolytic activities, which activated the KS and HD1 ${\delta}$-endotoxins, yielding the active toxins of about 65 kDa and the protease-resistant core of about 58 kDa. Moreover, the histopathological effects of KS and HD1 ${\delta}$-endotoxins on the larvae midgut consisted of an apical columnar cell vacuolization, microvillus damage, and epithelial cell disruption. These results showed that the KS strain could be a candidate for T. absoluta control.

• Bulletin of the Korean Chemical Society
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• 제18권6호
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• pp.618-622
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• 1997

The polysiloxane-bridged dinuclear metallocenes $[(SiMe_2O)_n-SiMe_2(C_5H_4)_2][(C_9H_7)ZrCl_2]_2$ (n=1 (7), 2 (8), 3 (9)) have been generated as a model complex for the immobilized metallocene at silica surface by treating the respective disodium salts of the ligands with 2 equivalents of $(C_9H_7)ZrCl_3$ in THF. All three complexes are characterized by $^1H$ NMR and measurement of metal content through ICP-MS. It turned out that the values of ${\Delta}{\delta}=[{\delta}_d-{\delta}_p]$, the chemical shift difference between the distal $({\delta}_d)$ and proximal $({\delta}_p)$ protons, for the produced dinuclear compounds (0.47 for 7, 0.49 for 8, and 0.5 for 9) were larger than the Δδ value of the known ansa-type complex holding the same ligand as a chelating one, that is just the opposite to the normal trend. In order to compare polymerization behavior of the dinuclear metallocene with the corresponding mononuclear metallocene, (Cp)$(C_9H_7)ZrCl_2$ was separately prepared. To investigate the catalytic properties of the dinuclear complexes and mononuclear metallocenes ethylene polymerization has been conducted in the presence of MMAO. The polymerization results display the typical activity dependence on polymerization temperature for all complexes. The most important feature is that the polymers from the dinuclear metallocenes represent enormously improved molecular weight compared with the polymer from the corresponding mononuclear metallocene. In addition, the influence of the nature of the bridging ligand upon the reactivities of the dinuclear metallocenes has also been observed.

• 한국식품과학회지
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• 제37권6호
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• pp.957-961
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• 2005

쌀엿 유통과정 중 변패를 일으키는 효모를 분리하여, 지방산 분석을 통하여 동정하였다. 분리된 균주의 지방산을 Microbial Identification system(MIDI)으로 분석하여 16:0, 16.1$({\Delta}cis\;7)$, 18:2$({\Delta}cis\;9)$, 18:1$({\Delta}cis\;9)$ 그리고 18:1의 탄소골격을 지닌 5가지 지방산을 확인하였다. 이 결과를 MIDI 데이터베이스와 비교하였으며 쌀엿 유통과정 중 변패를 일으킨 변패균을 Zygosaccharomyces bailii로 동정하였다. 쌀엿 변패균의 오염에 의한 쌀엿의 품질 저하를 방지하기 위하여 당도의 변화에 따른 쌀엿의 %수분함량과 수분활성도$(a_w)$의 관계를 연구하였다. 쌀엿의 당도를 약 $1^{\circ}brix$ 증가 시켰을 경우 약 1%의 수분함량이 감소하게 되는 반비례의 상관관계를 가짐을 알 수 있었다. 그리고 $77^{\circ}brix$에서$83^{\circ}brix$까지 당도가 증가하는데 수분활성도$(a_w)$가 0.09 감소하였다. $15^{\circ}C$ 및 $25^{\circ}C$에서 당도가 조정된 쌀엿에 변패균을 접종한 후 저장 시 변패균의 생육을 관찰하였다. $79^{\circ}brix$ 이하의 쌀엿에 변패균이 접종되었을 경우 모두 일정시간 동안 적은 균체 증가량을 나타내다가 급격한 균수의 증가 후 감소하는 생육 특징을 보였다. 그러나 $81^{\circ}brix$ 이상의 조건에서는 15, $25^{\circ}C$에 관계없이 접종 후 3-4주까지 급격한 균수의 감소를 보였으며, 이후에도 완만한 감소를 보이다 14주차부터 변패균의 생육이 더 이상 관찰되지 않았다. 결론적으로 쌀엿이 $81^{\circ}brix$, $25^{\circ}C$ 이하로 생산, 저장된다면 Z. bailii와 같은 변패균의 노출에 다른 피해를 방지할 수 있음을 알 수 있었다.

• BMB Reports
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• 제34권5호
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• pp.402-407
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• 2001

Based on the currently proposed toxicity model for the different Bacillus thuringiensis Cry $\delta$-endotoxins, their pore-forming activity involves the insertion of the ${\alpha}4-{\alpha}5$ helical hairpin into the membrane of the target midgut epithelial cell. In this study, a number of polar or charged residues in helix 4 within domain I of the 65-kDa dipteranactive Cry11A toxin, Lys-123, Tyr-125, Asn-128, Ser-130, Gln-135, Arg-136, Gln-139 and Glu-141, were initially substituted with alanine by using PCR-based directed mutagenesis. All mutant toxins were expressed as cytoplasmic inclusions in Escherichia coli upon induction with IPTG. Similar to the wild-type protoxin inclusion, the solubility of each mutant inclusion in the carbonate buffer, pH 9.0, was relatively low When E. coli cells, expressing each of the mutant proteins, were tested for toxicity against Aedes aegypti mosquito-larvae, toxicity was completely abolished for the alanine substitution of arginine at position 136. However, mutations at the other positions still retained a high level of larvicidal activity Interestingly, further analysis of this critical arginine residue by specific mutagenesis showed that conversions of arginine-136 to aspartate, glutamine, or even to the most conserved residue lysine, also abolished the wild-type activity The results of this study revealed an important determinant in toxin function for the positively charged side chain of arginine-136 in helix 4 of the Cry11A toxin.

• Mycobiology
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• 제40권3호
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• pp.173-180
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• 2012

A ${\beta}$-glucosidase from Penicillium italicum was purified with a specific activity of 61.8 U/mg, using a chromatography system. The native form of the enzyme was an 88.5-kDa tetramer with a molecular mass of 354 kDa. Optimum activity was observed at pH 4.5 and $60^{\circ}C$, and the half-lives were 1,737, 330, 34, and 1 hr at 50, 55, 60, and $65^{\circ}C$, respectively. Its activity was inhibited by 47% by 5 mM $Ni^{2+}$. The enzyme exhibited hydrolytic activity for p-nitrophenyl-${\beta}$-D-glucopyranoside (pNP-Glu), p-nitrophenyl-${\beta}$-D-cellobioside, p-nitrophenyl-${\beta}$-D-xyloside, and cellobiose, however, no activity was observed for p-nitrophenyl-${\beta}$-D-lactopyranoside, p-nitrophenyl-${\beta}$-D-galactopyranoside, carboxymetyl cellulose, xylan, and cellulose, indicating that the enzyme was a ${\beta}$-glucosidase. The $k_{cat}/K_m\;(s^{-1}mM^{-1})$ values for pNP-Glu and cellobiose were 15,770.4 mM and 6,361.4 mM, respectively. These values were the highest reported for ${\beta}$-glucosidases. Non-competitive inhibition of the enzyme by both glucose ($K_i=8.9mM$) and glucono-${\delta}$-lactone ($K_i=11.3mM$) was observed when pNP-Glu was used as the substrate. This is the first report of non-competitive inhibition of ${\beta}$-glucosidase by glucose and glucono-${\delta}$-lactone.

• 생명과학회지
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• 제17권5호
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• pp.658-663
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• 2007

B. thuringiensis는 많은 해로운 곤충들을 박멸시키는데 널리 사용되는 생물학적 살충제로 잘 알려져 있다. 그것은 측포자 형태의 결정체($\delta$-내독소)를 생산하고 내생포자들을 형성한다. 본 논문에서는 B. thuringiensis BT-1과 BT-2에 의해 생산되는 내독소의 특성을 주사전자현미경(SEM), 투과전자현미경(TEM), SDS-PACE, 알칼리 용액에서의 용해 활성을 통하여 규명하였다. BT-1, BT-2 균주는 GBY 배지에서 배양되었고, 두 균주의 내독소는 당밀도구배법을 이용하여 정제되어, 주사전자현미경(SEM), 투과전자현미경(TEM)으로 관찰하였다. 형태학적으로, BT-1의 내독소는 사각형 및 납작형이고 크기는 $1.73{\mu}m{\times}0.7{\mu}m$, 그리고 BT-2 내독소는 구형이며 $1.1{\mu}m$, 폭이 $0.9{\mu}m$인 것으로 밝혀졌다. SDS-PACE 방법으로 분석한 결과, BT-1의 분자량은 28 kDa, 21 kDa, 반면에 BT-2의 분자량은 50 kDa, 35 kDa, 22 kDal으로 밴드가 형성되었다. 이들의 결정체는 알칼리 완충용액 내에서 시간에 지나감에 따라서 점차로 용해되었으며 3시간 후에는 거의 완전하게 용해되었다. 이 결과들을 통하여 BT1과 BT-2 결정체의 내독소가 곤충의 중장 내에서 시간이 흐름에 따라 비활성 상태에서 활성상태로 전환되는 것으로 보여진다.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3709-3714
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• 2013

Based on the Debye-H$\ddot{u}$ckel equation, a semi-empirical equation for activity coefficients was derived through empirical and theoretical trial and error efforts. The obtained equation included two parameters: the proportional factor and the effective radius of an ionic sphere. These parameters were used in the empirical and regression parameter fitting of the calculated values to the experimental results. The activity coefficients calculated from the equation agreed with the data. Transforming to a semi-empirical form, the equation was expressed with one parameter, the ion radius. The ion radius, ${\alpha}$, was divided into three parameters, ${\alpha}_{cation}$, ${\alpha}_{anion}$ and ${\delta}_{cation}$, representing parameters for the cation, anion and combination, respectively. The advantage of this equation is the ability to propose a semi-empirical equation that can easily determine the activity coefficient with just one parameter, so the equation is expected to be used more widely in actual industry applications.

• BMB Reports
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• 제36권6호
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• pp.608-610
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• 2003

Escherichia coli has two catalases, HPI and HPII. HPI is induced during logarithmic growth in response to low concentrations of hydrogen peroxide. This induction is OxyR-dependent. On the other hand, HPII is not peroxide-inducible but is induced in entry to the stationary phase. We demonstrate here that E. coli displayed higher HPI catalase activity when compared to the cultures that were grown in a normal medium, if grown in a medium supplemented with iron-citrate. Iron supplementation had no effect on HPII catalase. This increase of HPI activity was OxyR-independent and not observed in a ${\Delta}fur$ mutant. The physiological significance of the increase of HPI activity is unclear, but it appears that the katG gene that codes for HPI catalase is among the genes that are regulated by Fur.

• 대한한의학회지
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• 제18권2호
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• pp.167-186
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• 1997

The inhibitory activity of Aquillariae Lignum (Thymelaeaceae) on type Ⅰ immediate hypersensitivity of the anaphylactic type in the wistar rat model of passive cutaneous anaphylaxis, an IgE-mediated, mast cell-dependent reaction. Administered orally at 250, 500 mg/kg body weight 1 h before the challenge, Aquillariae Lignum potently inhibited PCA in rats which disodium cromoglycate showed poor inhibitory activity. Aquillariae Lignum inhibited compound 48/80-induced anaphylaxis 100% with a dose of 0.5 g/kg body weight at 1 h before or 5 and 10 min after injection of compound 48/80. Aquillariae Lignum (0.05-1.6 mg/ml) also exhibited the dose-related inhibitory effect on compound 48/80-induced histamine release from rat_peritoneal mast cells. Moreover, it was clearly demonstrated that Aquillariae Lignum and disodium cromoglycate disodium cromoglycate potently inhibited such type Ⅰ allergic reactions as anaphylactic shocks, suggesting that these drugs, at least in part, share the same mechanism of action It is suggested that Aquillariae Lignum may exert a stronger inhibition on the mast cell degranulation process. Since Aquillariae Lignum (1.0 mg/ml) inhibited about 90% of histidine decarboxylase activity, the inhibitory activity of Aquillariae Lignum for histamine release was considered to be derived from the inhibition of histidine decarboxylase activity. It results from increased expression of the mRNA coding for histidine decarboxylase, as assessed by Northern blot analysis after a 12 h incubation to P-815 cells with dexamethasone plus 12-O-tetradecanoylphorbol-13-acetate. The addition of Aquillariae Lignum to P-815 cells with dexamethasone plus 12-O-tetradecanoyl-phorbol-13-acetate, significantly inhibited the histidine decarboxylase gene expression. Tumor necrosis $factor-{\alpha}$ was not constitutively expressed in P-815 cells. Substance P selectively activates the tumor necrosis $factor-{\alpha}$ gene expression in P-815 cells. Aquillariae Lignurm inhibited substance P-induced tumor necrosis $factor-{\alpha}$ gene expression. Furthennore, The effect of Aquillariae Lignum on the mRNA expression of novel protein kinase C ${\delta}$ a major isoform of mast cells, was examined by Northern blot analysis. The expression of novel protein kinase C ${\delta}$ mRNA in the presence of Aquillariae Lignum was significantly lower than in the absence of Aquillariae Lignum. These results suggest the possibility that the inhibition of allergic reaction by Aquillanae Lignum should be regulated by tumor necrosis $factor-{\alpha}$ and novel protein kinase C ${\delta}$.